One thought on “F-35 Operational Utility Evaluation cancelled in favour of crashing through to some future stage in hope”

1. This chart (thanks to David Archibald) speaks volumes about the increasing failure rate in F-35 evaluations over 20 years.
   
   Some copy n paste on the F-35 from the DOTE report – in the section headed “FY16 DOD PROGRAMS” starting pdf page 75
   F-35 Joint Strike Fighter
   Executive Summary
   Test Strategy, Planning, Activity, and Assessment
   • The Joint Strike Fighter (JSF) Program Office (JPO)
   acknowledged in 2016 that schedule pressure exists for
   completing System Development and Demonstration (SDD)
   and starting Initial Operational Test and Evaluation (IOT&E)
   by August 2017, the planned date in JPO’s Integrated Master
   Schedule. In an effort to stay on schedule, JPO plans to
   reduce or truncate planned developmental testing (DT) in
   an effort to minimize delays and close out SDD as soon as
   possible. However, even with this risky, schedule-driven
   approach, multiple problems and delays make it clear that
   the program will not be able to start IOT&E with full combat
   capability until late CY18 or early CY19, at the soonest.
   These problems include:
   — Continued schedule delays in completing Block 3F
   mission systems development and flight testing, which
   DOT&E estimates will likely complete in July 2018
   — Delayed and incomplete Block 3F DT Weapons Delivery
   Accuracy (WDA) events and ongoing weapons integration
   issues
   — Continued delays in completing flight sciences test points,
   particularly those needed to clear the full F-35B Block 3F
   flight envelope, resulting in a phased release of Block 3F
   envelope across the variants, with the full Block 3F
   envelope for F-35B not being released until mid-CY18
   — Further delays in completing gun testing for all three
   variants and recently discovered gunsight deficiencies
   — Late availability of verified, validated and tested Block 3F
   Mission Data Loads (MDLs) for planned IOT&E and
   aircraft delivery dates; DOT&E estimates the first
   validated MDLs will not be available until June 2018
   — Continued shortfalls and delays with the Autonomic
   Logistics Information System (ALIS) and late delivery of
   ALIS version 3.0, the final planned version for SDD, at
   risk of slipping from early CY18 into mid-CY18
   — Significant, well-documented deficiencies; for hundreds
   of these, the program has no plan to adequately fix and
   verify with flight test within SDD; although it is common
   for programs to have unresolved deficiencies after
   development, the program must assess and mitigate the
   cumulative effects of these remaining deficiencies on F-35
   effectiveness and suitability prior to finalizing and fielding
   Block 3F
   — Overall ineffective operational performance with multiple
   key Block 3F capabilities delivered to date, relative to
   planned IOT&E scenarios which are based on various
   fielded threat laydowns
   — Continued low aircraft availability and no indications
   of significant improvement, especially for the early
   production lot IOT&E aircraft
   — Insufficient progress in verification of Joint Technical
   Data, particularly those for troubleshooting aircraft fault
   codes and for support equipment
   — Delays in completing the required extensive and
   time‑consuming modifications to the fleet of operational
   test aircraft which, if not mitigated with an executable plan
   and contract, could significantly delay the start of IOT&E
   — Insufficient progress in the following areas which are
   required for IOT&E:
   ▪▪ Development, integration, and testing of the Air-to-Air
   Range Infrastructure instrumentation into the F-35
   aircraft
   ▪▪ Flight testing to certify the Data Acquisition, Recording,
   and Telemetry pod throughout the full flight envelope
   ▪▪ Development of other models, including the Fusion
   Simulation Model, Virtual Threat Insertion table, and
   the Logistics Composite Model
   — Delays in providing training simulators in the Block 3F
   configuration to the initial training centers and operational
   locations
   • Based on these ongoing problems and delays, and including
   the required time for IOT&E spin-up, the program will not
   be ready to start IOT&E until late CY18, at the soonest, or
   more likely early CY19. In fact, IOT&E could be delayed
   to as late as CY20, depending on the completion of required
   modifications to the IOT&E aircraft.
   Progress in Developmental Testing
   • Mission Systems Testing
   — The program continues to pursue a cost- and
   schedule‑driven plan to delete planned mission systems
   DT points by using other test data for meeting test point
   objectives in order to accelerate SDD close-out. This
   plan, if not properly executed with applicable data, sufficient analytical rigor and statistical confidence, would
   shift significant risk to operational test (OT), Follow-on
   Modernization (FoM) and the warfighter.
   — This risky approach would also discard carefully planned
   build-up test content in the Test and Evaluation Master
   Plan (TEMP) and the Block 3F Joint Test Plan (JTP),
   content the program fully agreed was required when
   those documents were signed. The program plans to
   “quarantine” JTP build‑up test points, which are planned
   to be flown by the test centers, and instead skip ahead
   to complex graduation‑level Mission Effectiveness Risk
   Reduction test points, recently devised to quickly sample
   full Block 3F performance. Then, if any of the Block 3F
   functionality appears to work correctly during the complex
   test points, the program would delete the applicable
   underlying build-up test points for those capabilities and
   designate them as “no longer required.” However, the
   program must ensure the substitute data are applicable and
   provide sufficient statistical confidence that the test point
   objectives had been met prior to deleting any underlying
   build-up test points. While this approach may provide a
   quick sampling assessment of Block 3F capabilities, there
   are substantial risks. The multiple recent software versions
   for flight test may prevent the program from using data
   from older versions of software to count for baseline test
   point deletions because it may no longer be representative
   of Block 3F. The limited availability and high cost of
   Western Test Range periods, combined with high re-fly
   rates for test missions completed on the range, make it
   difficult for the program to efficiently conduct this testing.
   Finally, the most complex capabilities in Block 3F have
   only recently reached the level of maturity to allow them
   to be tested, and they are also some of the most difficult
   test points to execute (i.e., full Block 3F capabilities and
   flight envelope).
   — Historical experience indicates this approach, if not
   properly executed, may delay problem discoveries and
   increase the risk to completing SDD and increase the risk
   of failure in IOT&E (as well as, much more importantly, in
   combat). In fact, the program needs to allocate additional
   test points – which are not in its current plans – for
   characterization, root cause investigations, and correction
   of a large number of the open high-priority deficiencies
   and technical debt described later in this report. The
   completion of the planned baseline test points from
   the Block 3F JTP, along with correction or mitigation
   of significant deficiencies, is necessary to ensure full
   Block 3F capabilities are adequately tested and verified
   before IOT&E and, more importantly, before they are
   fielded for use in combat.
   — Until recently, the Program Office estimated that mission
   systems flight testing will complete in October 2017. It
   now acknowledges the risk that this testing may extend
   into early CY18.
   ▪▪ The October 2017 estimate was based on an inflated
   test point accomplishment rate and optimistically low regression and re-fly rates. The estimate also assumed
   that the Block 3FR6 software, delivered to flight test
   in December 2016, would have the maturity necessary
   to complete the remaining test points and meet
   specification requirements without requiring additional
   versions of software to address shortfalls in capability.
   However, this is highly unlikely, since several essential
   capabilities – including aimed gunshots and Air-to-Air
   Range Infrastructure – had not yet been flight tested
   or did not yet work properly when Block 3FR6 was
   released.
   ▪▪ The Services have designated 276 deficiencies in combat
   performance as “critical to correct” in Block 3F, but less
   than half of the critical deficiencies were addressed with
   attempted corrections in 3FR6.
   ▪▪ Independent estimates from other Pentagon staff
   agencies vary from March 2018 to July 2018 to
   complete mission systems testing – all based on the
   current number of test points remaining and actual
   historic regression and re-fly rates from the flight test
   program. Even these estimates are optimistic in that
   they account for only currently planned testing, which
   does not yet include the activities needed to correct the
   Services’ remaining high-priority deficiencies.
   • Flight sciences testing continues to be a source of significant
   discovery, another indication that the program is not nearing
   completion of development and readiness for IOT&E. For
   example:
   — Fatigue and migration of the attachment bushing in the
   joint between the vertical tail and the aircraft structure are
   occurring much earlier than planned in both the F-35A
   and F-35B, even with a newly designed joint developed to
   address shortfalls in the original design.
   — Excessive and premature wear on the hook point of the
   arresting gear on the F-35A, occuring as soon as after only
   one use, has caused the program to consider developing a
   more robust redesign.
   — Higher than predicted air flow temperatures were measured
   in the engine nacelle bay during flight testing in portions
   of the flight envelope under high dynamic pressure on both
   the F-35A and F-35C; thermal stress analyses are required
   to determine if airspeed restrictions will be needed in this
   portion of the flight envelope.
   — Overheating of the horizontal tail continued to cause
   damage, as was experienced on BF-3, one of the
   F-35B flight sciences test aircraft, while accelerating in
   afterburner to Mach 1.5 for a loads test point. The left
   horizontal inboard fairing surface reached temperatures
   that exceeded the design limit by a significant amount.
   Post‑flight inspections revealed de-bonding due to heat
   damage on the trailing edge of the horizontal tail surface
   and on the horizontal tail rear spar.
   — Vertical oscillations during F-35C catapult launches were
   reported by pilots as excessive, violent, and therefore a
   safety concern during this critical phase of flight. The
   program is still investigating alternatives to address this
   deficiency, which makes a solution in time for IOT&E and
   Navy fielding unlikely.
   Mission Data Load Development and Testing
   • Mission data files, which comprise MDLs, are essential to
   enable F-35 mission systems to function properly. Block 3F
   upgrades to the U.S. Reprogramming Laboratory (USRL) –
   where mission data files are developed, tested and validated
   for operational use – are late to meet the needs for Block
   3F production aircraft and IOT&E. These upgrades to the
   Block 3F configuration, including the associated mission
   data file generation tools, are necessary to enable the USRL
   to begin Block 3F mission data file development. In spite
   of the importance of the mission data to both IOT&E and
   to combat, the Program Office and Lockheed Martin have
   failed to manage, contract, and deliver the necessary USRL
   upgrades to the point that fully validated Block 3F MDLs
   will not be ready for IOT&E until June 2018, at the earliest.
   • Operational units are also affected by the capability shortfalls
   in the USRL to create, test and field MDLs. The complete
   set of Block 2B and Block 3i MDLs developed for overseas
   areas of responsibility (AORs) have yet to undergo the full
   set of lab and flight tests necessary to validate and verify
   these MDLs for operational use. Because of the delays
   in upgrading the USRL to the Block 3F configuration, the
   Services will likely not have Block 3F MDLs for overseas
   AORs until late 2018 or early 2019.
   • In addition to the late Block 3F USRL upgrades, the required
   signal generators for the USRL – with more high-fidelity
   channels to simulate modern fielded threats – have not yet
   been placed on contract. As a result, the Block 3F MDLs
   will not be tested and optimized to ensure the F-35 will
   be capable of detecting, locating, and identifying modern
   fielded threats until 2020, per a recent program schedule.
   The program is developing multiple laboratories in order
   to produce MDLs tailored for partner nation-unique
   requirements, some of which will have more high-fidelity
   signal generator channels earlier than the USRL. The
   program is considering using one of these other laboratories
   for Block 3F MDL development and testing; however,
   the MDL that will be used for IOT&E must be developed,
   verified, validated, and tested using operationally
   representative procedures, like the MDLs that will be
   developed for the operational aircraft in the USRL.
   Weapons Integration and Demonstration Events
   • Block 3F weapons delivery accuracy (WDA) events are
   not complete. These events, required by the TEMP, are key
   developmental test activities necessary to ensure the full
   fire-control capabilities support the “find, fix, track, target,
   engage, assess” kill chain. As of the end of November,
   only 5 of the 26 events (excluding the gun events) had been
   completed and fully analyzed. Several WDAs have revealed
   deficiencies and limitations to weapons employment (e.g.,
   AIM-9X seeker status tone problems and out-of-date launch
   zones for AIM-120 missiles). An additional 11 WDAs had
   occurred, but analyses were ongoing. Of the 10 remaining
   WDAs that had not been completed, 4 were still blocked
   due to open deficiencies that must be corrected before the
   WDA can be attempted. However, the program did not
   have time to fix the deficiencies, complete the remaining
   WDAs and analyze them before finalizing Block 3FR6 in
   late November for flight testing to begin in December 2016.
   For example, recent F-35C flight testing to prepare for a
   weapons event with the C-1 version of the Joint Stand-Off
   Weapon (JSOW-C1) discovered weapon integration,
   Pilot Vehicle Interface (PVI) and mission planning problems
   that will prevent full Block 3F combat capability from
   being delivered, if not corrected. These discoveries were
   made too late to be included in the Block 3FR6 software,
   the final planned increment of capability delivered to flight
   test for SDD. Also, multiple changes are being made late
   in Block 3F development to mission systems fire control
   software to correct problems with the British AIM-132
   Advanced Short-Range Air-to-Air Missile (ASRAAM)
   missile and Paveway IV bomb, changes which could affect
   the U.S. AIM-9X air‑to‑air missile and GBU-31 laser-guided
   bomb capabilities, and may require regression testing of the
   U.S. weapons.
   • Block 3F adds gun capability for all variants. The F-35A
   gun is internal; the F-35B and F-35C each use a gun pod.
   Ground firing tests have been completed on all variants;
   only on the F-35A has initial flight testing of the gun been
   accomplished. Early testing of the air-to-ground and
   air-to-air symbology have led to discovery of deficiencies in
   the gunsight and strafing symbology displayed in the pilot’s
   helmet – deficiencies which may need to be addressed before
   accuracy testing of the gun, aimed by the HMDS, can be
   completed. Because of the late testing of the gun and the
   likelihood of additional discoveries, the program’s ability
   to deliver gun capability with Block 3F before IOT&E is at
   risk, especially for the F-35B and F-35C.
   Pilot Escape System
   • The program completed pilot escape system qualification
   testing in September 2016, which included a set of
   modifications designed to reduce risk to pilots weighing less
   than 136 pounds.
   — Modifications include:
   ▪▪ Reduction in the weight of the pilot’s Generation III
   Helmet Mounted Display System (HMDS), referred to
   as the Gen III Lite HMDS
   ▪▪ Installation of a switch on the ejection seat which
   allows lighter-weight pilots to select a slight delay in the
   activation of the main parachute
   ▪▪ Addition of a Head Support Panel (HSP) between the
   risers of the parachute.
   — These modifications to the pilot escape system were
   needed after testing in CY15 showed that the risk of
   serious injury or death is greater for lighter-weight pilots.
   Because of the risk, the Services decided to restrict pilots
   weighing less than 136 pounds from flying the F-35.
   • Twenty-two qualification test cases were completed
   between October 2015 and September 2016, with variations
   in manikin weight, speed, altitude, helmet size and
   configuration, and seat switch setting. Data from tests
   showed that the HSP significantly reduced neck loads
   under conditions that forced the head backwards, inducing
   a rearward neck rotation, during the ejection sequence.
   Data also showed that the seat switch reduced the “opening
   shock” by slightly delaying the main parachute for lighterweight
   pilots at speeds greater than 160 knots. The extent
   to which the risk has been reduced for lighter-weight pilots
   (i.e., less than 136 pounds) by the modifications to the
   escape system and helmet is still to be determined by a
   safety analysis of the test data. If the Services accept the
   risk associated with the modifications to the escape system
   for the lighter-weight pilots, restrictions will likely remain in
   effect until aircraft have the modified seat and the HSPs, and
   until the lighter‑weight Gen III Lite helmets are procured and
   delivered to the applicable pilots.
   • Based on schedules for planned seat modifications,
   production cut-in of the modified seat, and the planned
   delivery of the Gen III Lite HMDS, the Air Force may be
   able to reopen F-35 pilot training to lighter-weight pilots
   (i.e., below 136 pounds) in early 2018. DOT&E is not aware
   of the plans for the Marine Corps and the U.S. Navy to open
   F-35 pilot training to the lighter-weight pilots.
   • Part of the weight reduction to the Gen III Lite HMDS
   involved removing one of the two installed visors (one
   dark, one clear). As a result, pilots that will need to use
   both visors during a mission (e.g., during transitions from
   daytime to nighttime) will have to store the second visor in
   the cockpit. However, there currently is not enough storage
   space in the cockpit for the spare visor, so the program is
   working a solution to address this problem.
   • The program has yet to complete the additional testing and
   analysis needed to determine the risk of pilots being harmed
   by the Transparency Removal System (which shatters the
   canopy first, allowing the seat and pilot to leave the aircraft)
   during off-nominal ejections in other than ideal, stable
   conditions (such as after battle damage or during out-ofcontrol
   situations). Although the program completed an
   off-nominal rocket sled test with the Transparency Removal
   System in CY12, several aspects of the escape system have
   changed since then (including significant changes to the
   helmet) which warrant additional testing and analyses.
   Joint Simulation Environment (JSE)
   • JSE is a man-in-the-loop, F-35 mission systems software-inthe-
   loop simulation being developed to meet the operational
   test requirements for Block 3F IOT&E. However, multiple
   aspects of the JSE development effort continue to fall
   significantly behind schedule. The Program Office has been
   negotiating with the contractor to receive the F-35 aircraft
   and sensor models, referred to as “F-35 In A Box (IAB),”
   but very limited progress was made in CY16. Also, delays
   with security clearances for new personnel limited progress
   on several aspects of the development and validation effort.
   Although the Naval Air Systems Command (NAVAIR)
   government team has begun installing hardware on their
   planned timeline (facilities, cockpits, etc.), the team’s
   progress in integrating the many different models (i.e.,
   multi‑spectral environment, threats, weapons) with F-35 IAB
   has been severely limited, and the verification, validation and
   accreditation of these models within JSE for use in IOT&E,
   have effectively stalled. The F-35 program’s JSE schedule
   indicates that it plans to provide a fully accredited simulation
   for IOT&E use in May 2019; a schedule that carries high
   risk of further slips without resolving these issues, and is
   not credible. Without a high-fidelity simulation, the F-35
   IOT&E will not be able to test the F-35’s full capabilities
   against the full range of required threats and scenarios.
   However, for the reasons above, it is now clear that the JSE
   will not be available and accredited in time to support the
   Block 3F IOT&E. Therefore, the recently approved IOT&E
   detailed test design assumes only open-air flight testing will
   be possible and attempts to mitigate the lack of an adequate
   simulation environment as much as possible. In the unlikely
   event the JSE is ready and accredited in time for IOT&E, the
   test design has JSE scenarios that would be conducted.
   Live Fire Test and Evaluation (LFT&E)
   • The F-35 LFT&E program completed one major live fire test
   series using an F-35C variant full-scale structural test article
   (CG:0001). Preliminary test data analyses:
   — Demonstrated the tolerance of the vertical tail attachments
   to high-explosive incendiary (HEI) projectile threats
   — Confirmed the tolerance of the aft boom structures to
   Man-Portable Air Defense System (MANPADS) threats
   — Demonstrated vulnerabilities to MANPADS-generated
   fires in engine systems and aft fuel tanks. The data
   will support a detailed assessment in 2017 of these
   contributions to overall F-35 vulnerability.
   • The test plan to assess chemical and biological
   decontamination of pilot protective equipment is not
   adequate; no plans have been made to test either the Gen II
   or the Gen III HMDS. The Program Office is on track
   to evaluate the chemical and biological agent protection
   and decontamination systems in the full-up system-level
   decontamination testing in FY17.
   • The Navy conducted vulnerability testing of the F-35B
   electrical and mission systems to electromagnetic pulses
   (EMP).
   • The 780th Test Squadron at Eglin AFB, Florida completed
   ground-based lethality tests of the PGU-47/U Armor
   Piercing High Explosive Incendiary with Tracer (APHEI-T)
   round, also known as the Armor Piercing with Explosive
   (APEX), against armored and technical vehicles, aircraft, and
   personnel-in-the-open targets.
   Suitability
   • The operational suitability of all variants continues to be
   less than desired by the Services. Operational and training
   units must rely on contractor support and workarounds that
   would be challenging to employ during combat operations.
   In the past year some metrics of suitability performance have
   shown improvement, while others have been flat or declined.
   — Most metrics still remain below interim goals to achieve
   acceptable suitability by the time the fleet accrues 200,000
   flight hours, the benchmark set by the program and defined
   in the Operational Requirements Document (ORD)
   for the aircraft to meet reliability and maintainability
   requirements.
   — Reliability growth has stagnated and, as a result, it is
   highly unlikely that the program will achieve the ORD
   threshold requirements at maturity for the majority
   of reliability metrics, most notably Mean Flight
   Hours Between Critical Failures, without redesigning
   components of the aircraft.
   Autonomic Logistics Information System
   • The program failed to release any new ALIS capability
   in 2016, but did release two updates to the currently fielded
   ALIS 2.0.1 software to address deficiencies and usability
   shortfalls. The program planned to test and field ALIS 2.0.2,
   including integration of propulsion data management, in
   the summer of 2016, to support the Air Force declaration
   of Initial Operational Capability; however, delays in
   development and integration have pushed the testing and
   fielding into 2017.
   • Because of the delays with ALIS 2.0.2, Lockheed Martin
   shifted personnel to support that product line development.
   This caused delays in the development schedule of ALIS 3.0,
   the last major SDD software release. The program
   acknowledged in August 2016 that it could not execute the
   ALIS 3.0 schedule and developed plans to restructure this
   ALIS release and the remaining planned ALIS capabilities
   into multiple releases, including some that will occur after
   SDD completion.
   — The program’s restructuring of the ALIS capability
   delivery plan divided the planned capabilities and security
   updates for ALIS into four more versions: one version for
   SDD (ALIS 3.0), with what the Program Office considered
   to be needed for IOT&E, and three additional software
   releases intended to be fielded at 6-month intervals after
   SDD completion, with the remaining content originally
   planned for ALIS 3.0.
   — The program plans to release software maintenance
   updates midway between each of these four software
   releases to address deficiencies and usability problems, but
   these releases will not include new capabilities.
   • The Air Force completed its first deployment of F-35A
   aircraft using the modularized version of the ALIS squadron
   hardware, called the Standard Operating Unit Version 2
   (SOU v2), and software release 2.0.1 to Mountain Home
   AFB, Idaho in February 2016. Difficulties integrating the
   SOU v2 into the base network interfered with connectivity
   between the SOU v2 and the Mountain Home-provided
   workstations, but did not affect connectivity of the SOU v2
   with the main Autonomic Logistics Operating Unit (ALOU)
   in Fort Worth, Texas.
   Air-Ship Integration and Ship Suitability
   • The program completed the last two ship integration DT
   periods in 2016 – both referred to as “DT-III” – one with
   the F-35B in November aboard the amphibious assault ship
   USS America, and one with the F-35C in August aboard the
   aircraft carrier USS George Washington. Test objectives
   included expanding the flight clearances for shipboard
   operations with carriage of external weapons, night
   operations, and Joint Precision Approach Landing System
   (JPALS) integration testing. For both periods, operational
   and test units accompanied the deployment to develop
   concepts of operations for at-sea periods.
   • The specialized secure space set aside for F-35-specific
   mission planning and the required Offboard Mission
   Support (OMS) workstations is likely unsuitable for regular
   Air Combat Element (ACE) operations on the Landing
   Helicopter Dock (LHD) and Landing Helicopter Assault
   (LHA)-class assault ships with the standard complement
   of six F-35B aircraft, let alone F-35B Heavy ACE
   configurations with more aircraft. Similarly, for F-35C
   operations onboard CVN, adequate secure spaces will be
   needed to ensure planning and debriefing timelines support
   carrier operations.
   • The F-35C DT-III included external stores, including bombs,
   but only pylons with no AIM-9X missiles on the outboard
   stations (stations 1 and 11) due to the F-35C wingtip
   structural deficiency. The U.S. Navy directed a proof-ofconcept
   demonstration of an F-35C engine change while
   underway, a process that took several days to complete.
   ALIS was not installed on USS George Washington, so
   reach-back via satellite link to the shore-based ALIS unit was
   required, similar to previous F-35C test periods at sea, but
   connectivity proved troublesome.
   • The F-35B DT-III deployment included an engine
   installation due to required maintenance, along with a lift fan
   change proof‑of‑concept demonstration. The Marine Corps
   deployed with an operational SOU v2 on USS America.
   Cybersecurity Testing
   • The JSF Operational Test Team (JOTT) continued to conduct
   cybersecurity testing on F-35 systems, in partnership with
   certified cybersecurity test organizations and personnel, and
   in accordance with the cybersecurity strategy approved by
   DOT&E in February 2015. In 2016, the JOTT conducted
   adversarial assessments (AA) of the ALIS 2.0.1 SOU, also
   known as the Squadron Kit, at Marine Corps Air Station
   (MCAS) Yuma, Arizona, and the Central Point of Entry
   (CPE) at Eglin AFB, Florida, completing testing that began
   in the Fall of 2015. They also completed cooperative
   vulnerability and penetration assessments (CVPA) of the
   mission systems ALOU at Edwards AFB, California, used
   to support developmental testing, and the operational ALOU
   in Fort Worth, Texas. The JOTT, with support from the