aerospace

JAL516 / JA722A crash at RJTT (Haneda) 02.01.2024

mathias

after reviewing a number of sources presented at different sites, I would like to add a few more points and present my early analysis of the likely causal events for the accident (isolated on this site, without adding to the speculations winding up elsewhere. let’s wait for the official report from JTSB – and compare).

current facts as presented from official sources:

  1. METAR: RJTT 020900Z 33008KT 9999 FEW020 07/04 Q1016 NOSIG
  2. NOTAM J2253/23: [..] STOP-BAR-LGT FOR C1 THRU C14-U/S [..]
  3. ATC transcript (released by Japanese Ministry of Transportation)
    • JAL516 had received landing clearance RWY 34R, positive readback.
    • JA722A taxi to holding point C5 (34R) for #1 in sequence, positive readback.
    • and additionally:
    • JAL166 to continue approach as #2 in sequence, positive readback
    • JAL179 to taxi to holding point C1 (34R) for #3 in sequence, positive readback

Primary question: Why did JA722A, contrary to its clearance, not hold at C5 but entered 34R ? Secondary questions of course relate to: 1) why did TWR (visually or by automated means) not identify the deviation and initiated corrective actions, 2) why was JAL516 unable to identify the abnormal condition and initiated a go-around in time.

While there is a lot to analyze on the environment and procedures related to the secondary set of questions, at this point in time, I would like to solely focus on the primary question. All assertions are speculative in nature and provided with plausible justification:

  1. official sources state that JA722A was a Japanese Coast Guard flight related to Jan 01 24 earthquake disaster relief. It is highly likely that in its flight plan JA722A was given status as a rescue flight and as such was given priority by coordinating stations, including Tokyo TWR.
  2. Consistent with (1) JA722A was cleared to hold for a (non-standard – but acceptable due to the aircraft’s lower requirement on take-off runway available) intersection (C5) take-off on RWY 34R. Tower assigned JA722A as #1 in sequence for runway 34R, relative to #2 JAL166 on approach, behind JAL516 (which has just been given already clearance to land) and to #3 JAL179 on ground for departure, cleared to taxi to (standard) holding point C1, about 30 seconds after JA722A had receive its assignment to C5. Therefore, TWR had indeed prepared a priority sequencing for JA722A, putting it ahead of competing JAL179 (which it would likely have followed to C1) and scheduling it’s departure between landing JAL516 and approaching JAL166. The effective sequence at this point in time was:
    • #0 JAL516: on final, cleared to land 34R
    • #1 JA722A: on ground, to hold at C5, 34R
    • #2 JAL155: on approach, to continue approach 34R
    • #3 JAL179: on ground, to hold at C1, 34R
  3. TWR in it’s communicated sequencing (starting at #1) did not further mention aircraft #0. In fact JA722A and JAL516 obviously being on the same frequency, situational awareness of the JA722A crew would have allowed them to pick up JAL516’s landing clearance right before receiving their clearance to hold at C5. Only in the case that TWR would have considered issuing a conditional “line up and wait” clearance to JA722A (such as: “JA722A line up RWY 34R and wait BEHIND landing aircraft on final BEHIND”) TWR would have mentioned the landing traffic.
  4. On CCTV footage from the airport camera (www.youtube.com/watch?v=6NbVdIoJsHY&t=169, Note: Please enlarge the video to full screen and monitor the faint white dot moving just above the upper edge of the tail of the distant ANA aircraft that just started taxiing from the illuminated area of the apron towards the darker runway area), at video time 3:00 one can see JA722A to enter 34R and wait in a position aligning with the runway as its landing light turns (left) towards the camera and distinctly grows brighter. From this moment on, JA722A is holding position on RWY 34R for an eternity of 48 (!) seconds – apparently waiting for a take-off clearance – before being impacted by the landing JAL516. On the video one can occasionally distinguish the JA722A strobe lights first moving and then holding with the aircraft, but its red flashing beacon is not visible on the recording.
  5. The captain of JA722A was reported to be the sole survivor of this aircraft and (unconfirmed) Japanese Coast Guard sources quote him as being conscious of having received a clearance to (at least) enter RWY 34R. If the captain (LH seat) was pilot flying (PF) and RH seat was pilot monitoring (PM), there is obviously a “connection” between the captain’s statement and the apparent action of the aircraft, but a huge “disconnect” with the ATC clearance (to hold at C5) which was properly read back from the aircraft. In essence, this appears to be a catastrophic disconnect between the mental models of PF and PM. In addition, there are possible physical factors contributing to the fatal actions taken by the crew:
    • (1) If PM was distracted by monitoring ATC (in English language), preparing the aircraft (working the checklists) for priority departure as #1 in sequence, PM (in his RH seat, not being the captain) was likely the only one two have an unobstructed view before line-up towards the arrival end of RWY 34R to spot (in very good visual conditions, see METAR at source 1 above) landing- & strobe-lights of JAL516. PF was likely not in this visual position, and likely not advised by PM, as this would be the case in a cockpit with well established CRM.
    • (2) As stated in source 2, NOTAM indicates that runway stop lights at C5 (and other intersections) were un-serviceable. With regard to the validity of the NOTAM however, additional caution has to be exercised since further provisions in the AIP Japan and possible trigger NOTAMs may be required. If stop-bar lights were indeed not operational, the crew (and specifically PF) would lack an additional clue that the mental model of having received a clearance for line-up was invalid.
  6. Possible causative mental factors, such as disorientation and stress within the cockpit of JA722A could be:
    • (1) night operations at a major international airport, ATC in English language, a non-commercial (coast guard) crew.
    • (2) a sense of urgency and stress perceived by a likely “rescue mission” flight status and an effective priority handling, being assigned #1 in sequence for RWY 34R.
  7. Adding to (6) but being HIGHLY SPECULATIVE in nature, I listened to ATC recordings from Tokyo TWR (remark: I have for myself ICAO English Level 6 printed in my license, but I have to admit that Haneda TWR communications in English by non-native Japanese speakers are EXTREMELY DIFFICULT to follow) on an (amateur) source www.youtube.com/watch?v=LP1xWcyKBDs&t=912s. In fact, those Internet resources usually pool together reception of several TWR frequencies – serving different parts of the airport – in a single audio stream). At the entry point marked (15:13) the recording starts with the C5 holding clearance given to JA722A (note: the documented readback from the aircraft however has not been picked-up on this specific recording – possibly due to low radio signal strength). However, at 15:24, immediately afterwards, one can hear a clearance given to another aircraft on runway 05 to “line up and wait runway zero five”. In a state of mental stress, let’s assume the following:
    • (1) JA722A had initially prepared a radio setup for several possible TWR frequencies, having the one pertaining to RWY 34R selected “active” and another frequency (for RWY 05) selected “stand-by”, possibly monitoring. Depending on the radio equipment of the aircraft, it is possible to simultaneously monitor (listen only) the stand-by frequency while being able to listen & speak on the active one. If this was intentionally or accidentally selected by the crew, then
    • (2) If the mental model of PF was anticipating an expedite #1 departure out of “charlie five” by a soon to follow order to line up, the audible reception of “runway zero five, line up and wait” could be “joined” into the PF’s mental model via the word “five” and his expectation on clearance to enter the runway. The consequence would match exactly the fatal actions taken by the aircraft: line up and wait.
  8. One could speculate that crew communication on board Japanese Coast Guard’s JA722A was obeying to a more military “chain of command” and challenging a decision of a senior party (here: PF, captain) by a junior party (here: PM) is not a strong point in Asia, as this might further be a matter in Japanese culture. This being said, there was perhaps too little room for questioning and corrective action inside the cockpit – sadly within an extensively long waiting time right in the middle of an active runway.

Abbreviations: METAR (meteorological aerodrome report), NOTAM (notice to airmen), AIP (aeronautical information publication), RWY (runway), CRM (crew resource management), ATC (air traffic control), TWR (tower), RH (right hand), LH (left hand)

StratoExplorer 2.0 / pre-launch (1/4)

mathias

Introduction

StratoExplorer is a privately operated technology demonstration for an edge-of-space flight of a stratospheric balloon probe. High altitude ballooning (HAB) got popular in recent years to send all sorts of electronics gadgets (such as smartphones, action-cams, sat-trackers) to the upper atmosphere – and eventually return and retrieve them safely. In contrast, StratoExplorer project focus is set on:

  • engineering (digital electronics, hardware) of lightweight and robust payload
  • software design and implementation (fault-tolerant, x-architecture, x-language: C++, Py)
  • long-range telemetry and IoT connectivity (multi-sensor, data replication, monitoring)

The project relies on ARM-Cortex M7 (“Teensy 4.1”) and ESP8266-12E micro-controller hardware for probe (“StratoExplorer”) and (mobile) ground station (“StratoExplorerRX”) respectively. Both devices make use of identical, proprietary libraries for task scheduling, data sampling and air-ground communications via 433 MHz LoRa. Moreover, both units are synchronized to GPS-based reference time. Therefore, switching of LoRa spreading factors (data rate and range) and bi-directionality (airborne probe acknowledges up-link messages) are available. For the “human” interface, an InfluxDb + Grafana stack is operated on raspberry-pi hardware: a) a Pi-zero device in a LAN with a smartphone (as: display, WiFi access point, Internet gateway), b) a Pi-4 device with replicated telemetry for “world”-access.

StratoExplorer: architecture diagram

StratoExplorerRX preview:

PyStratoExplorerRX “Cockpit” receiving (test) telemetry data from StratoExplorerRX. This gives an impression of the air-to-ground telemetry data received by the ground station: direct and derived information.

PyStratoExplorerRX cockpit web-interface, showing critical telemetry data and map view of 3 targets: payload, predicted landing site, tracking receiver.

Status & next steps

  • done:
    • Successful integration-testing-I (hw/sw, static non-flight) of StratoExplorer, StratoExplorerRX & PyStratoExplorerRX
  • next:
    • physical mounting of hardware + (long range) telemetry testing
    • integration-testing-II (hw/sw, simulated flight)
    • assembly with balloon + parachute and camera units
    • legal paperwork and flight scheduling
  • expect further pre-launch posts:
    • 2/4: StratoExplorer 2.0: payload details
    • 3/4: (Py)StratoExplorerRX details
    • 4/4: reports from telemetry testing & integration-test-II

microgravity in parabolic flight

mathias

For if one considers an observer in free fall, e.g. from the roof of a house, there exists for him during his fall no gravitational field

Albert Einstein (1907, “happiest thought of my life”)

mid September 2021 at the Dübendorf Swiss Airforce field, close to Zürich: After almost 2 years of waiting due to the covid-19 pandemic and its effects on aerospace activities, I was very happy to finally stand on the tarmac right next to the Zero-G Airbus A310. The aircraft has modified controls and therefore is released in the “experimental” category. With a total of three pilots who independently operate pitch, roll and throttle during parabolic flight, ballistic parabolas can be flown with high precision. In fact, the plane is routinely used by ESA for training missions, for international research and, capacity permitting, also for chartered flights.

This flight was mentored by ESA senior astronaut Jean-François Clervoy (that lucky guy flew on board the Space Shuttle for 3 times and took part in the EVAs for in-flight repair of the Hubble Space Telescope). We flew a total of 14 zero-g parabolas and 2 additional parabolas with marsian (3.7 m/s2) and lunar (1.6 m/s2) gravity respectively.

J-F. Clervoy and me

The flight track went from Zürich via Grenoble to the Côte d’Azur and to a position abeam the northern tip of Sardinia – and back. The crew kept everyone well informed about the sequence of maneuvers: Countdown to an initial raise in pitch angle (“pull-up”, during which we experience roughly 2g of “heaviness”) … 10° … then climbing steeper 30° … up to (a pilot’s horror) 50° nose-up attitude:

“Injection !”, engine noise is reducing to idle and here we are: Weightless for about 25 seconds – what a beautiful sensation, I could not get enough from it !

Eventually, the voice from the cockpit is counting backwards for “pull-out”, smashing everyone back to that side of the aircraft’s interior designated by the gravitational field of the Earth to be the floor rather than its ceiling. For the first few parabolas, I had to admit to myself that all prior mental or physical resolutions on how to best deal with weightlessness had to be thrown overboard and experience had to be gathered by practice.

inside the Zero-G Airbus A310

Just a few notes:

  • The vestibular system is unable to work reliably without the usual gravitational acceleration from “below”. It’s absence however is masked by all kind of other accelerations you pick up by either pushing yourself against the aircraft interior or absorb momentum from other people bumping their body parts into yours. With only visual reference remaining in a nearly all-white cabin, after a few pirouettes, it’s really hard to evaluate the true orientation of one’s body.
  • Once a parabola comes to it’s end, it is vital to make sure you have your feet where your feet are supposed to be when gravity is “turned back on” again. I remember one incident when I was floating right behind the back of another person, taking a glimpse through his pair of legs, eventually finding my head close to his ankles when I heard the countdown towards pull-out. The initial thought of: “I am right, the other guy must be wrong” quickly turned into despair realizing that the other person was one of the cabin safety staff who was correctly “standing” towards firm ground – while I was set to land head first. Eventually, he gave me a helping hand to hurdle me around before it was too late.
  • While floating in the cabin, it is quite difficult to keep a stable position in order to take pictures. The laws of physics, specifically the conservation of (angular) momentum, are playing constant games with you. If you abruptly stretch your arm in a certain direction, i.e. to reach out for a hold or to do an intuitive balance movement, you are actually propelled away into the opposite direction. As a consequence, for the first few parabolas I was floundering around quite helplessly. Eventually, I learned to smoothen my movements and adopt a more “zen” attitude towards the zero-g environment.

two zero-g scenes filmed by myself:

Knowing the sensation of jumping from a springboard, or from turbulence aboard an aircraft, I was prepared to encounter weightlessness as an overwhelming or perhaps fearful sensation of falling. But it wasn’t at all like this ! The effect sets in very smoothly without the nauseating feeling of falling (Note: We could not look outside. For the initial half of the zero-g phase, the aircraft was actually still climbing on a ballistic trajectory for approx. 850m, post apogee falling for the same distance prior to “pull-out”). What prevails is the sensation of feeling light as a feather while still being conscious of one’s own mass.

Finally, here’s a reference to a nice explanatory video from a different flight and crew:

Insights into the complex flying technique, Video by Tom Scott