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Tehran / 1976 Iran F-4 Incident

Date / time : Night of 18–19 September 1976; initial civilian calls ~22:30 local, F 4 scrambles beginning ~01:30 Location : Airspace over Tehran and northern environs, Imperial Iran; ground trace site on a dry lake bed southwest of the city Witnesses : Multiple civilian telephon…

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Tehran / 1976 Iran F-4 Incident ( 1976-09-19 · Tehran, Iran )

Quick facts

  • Date / time: Night of 18–19 September 1976; initial civilian calls ~22:30 local, F-4 scrambles beginning ~01:30
  • Location: Airspace over Tehran and northern environs, Imperial Iran; ground-trace site on a dry lake bed southwest of the city
  • Witnesses: Multiple civilian telephone callers from the Shemiran district; night-shift supervisor Hossain Perouzi (Mehrabad Airport); General Nader Yousefi (base balcony observer); Capt. Aziz Khani and 1st Lt. Hossein Shokri (first F-4 crew); Squadron Commander Parviz Jafari and 1st Lt. Jalal Damirian (second F-4 crew); crew of a civil airliner; ground residents near the dry lake bed
  • Shape / description: Large primary object described as rectangular/cylindrical (~7–8 m long × ~2 m wide) with pulsating whitish-blue light at both ends and a small red light orbiting the midsection; later described as diamond-shaped with intense strobing red, green, orange, and blue lights; radar return equivalent in size to a Boeing 707; multiple smaller spherical sub-objects
  • Duration: Approximately 2–3 hours of sustained activity (22:30 Sept. 18 through early morning Sept. 19); follow-up ground investigation at dawn
  • Classification: Hynek CE-II (close encounter with physical/EM effects); USAF/DIA "Unknown" — explicitly rated a classic UFO case
  • Status: Unexplained / unresolved — DIA assessed it as meeting all criteria for a bonafide UFO phenomenon study; no conventional explanation has been publicly confirmed

Media

Media here is presented as source/context material, not as proof of an extraordinary explanation. Captions preserve provenance and distinguish contextual visuals from direct evidence.

Tehran / 1976 Iran F-4 Incident ( 1976-09-19 · Tehran, Iran ): 1976 Tehran UFO incident 1976 Tehran UFO incident — wikipedia; license not stated; relevance: context. Source page.

Tehran / 1976 Iran F-4 Incident ( 1976-09-19 · Tehran, Iran ): Iran CIA map 1982.jpg Iran CIA map 1982.jpg — wikimedia commons; Public domain; relevance: context. Attribution: CIA. Source page.

Tehran / 1976 Iran F-4 Incident ( 1976-09-19 · Tehran, Iran ): Tehran ufo 1976 1.jpg Tehran ufo 1976 1.jpg — wikimedia commons; Public domain; relevance: context. Attribution: Captain Henry S. Shields. Source page.

Narrative

Between 22:30 and 23:15 on the night of 18 September 1976, the control tower at Mehrabad Airport began receiving telephone calls from residents of the Shemiran district of northeastern Tehran, reporting an unknown object hovering approximately 1,000 feet (300 m) above the city [S4]. Initial calls described the object variously as "bird-like" or as a brightly lit helicopter, even though the command post confirmed no helicopters were airborne at the time [S3][S8]. Night shift supervisor Hossain Perouzi initially dismissed the reports, but after a fourth call at approximately 23:15 he went to the tower terrace with binoculars and made his own observation [S4]. He described the object as rectangular in shape — approximately seven to eight metres long and two metres wide — cylindrical in profile, with both ends pulsating whitish-blue and a small red light circling its midsection [S4]. Perouzi contacted the Air Force command post at approximately 00:30 on 19 September; General Nader Yousefi, base operations commander and the third-ranking officer in the Imperial Iranian Air Force (IIAF), stepped onto the balcony of his Tehran residence, confirmed the sighting, and authorised a scramble [S3][S4][S6].

The first F-4 Phantom II, crewed by Capt. Aziz Khani and 1st Lt. Hossein Shokri, was launched from Shahrokhi Air Force Base (present-day Hamadan Airbase) at approximately 01:30 [S14]. As the aircraft closed to roughly 25 nautical miles (approximately 45 km) from the object, the crew suddenly lost all UHF communications, intercom, and flight instrumentation [S3][S13]. The moment the pilot broke off the intercept and turned back toward base, all systems returned to normal — a directional, repeatable effect that ruled out routine avionics failure [S3][S8]. Lt. General Azarbarzin, Deputy Commander-in-Chief of Operations of the IIAF, later confirmed publicly that the jamming was unlike anything in the Iranian or American inventories: a very wide-band signal capable of simultaneously jamming multiple different frequencies, rendering the aircraft's avionics entirely inoperable [S6][S11].

Ten minutes later, at approximately 01:40, a second F-4 piloted by Squadron Commander Parviz Jafari with 1st Lt. Jalal Damirian in the back seat was scrambled [S14]. The UFO was visible at roughly 70 miles' distance [S3][S7] and picked up on the F-4's radar at approximately 27 miles, producing a return the size of a Boeing 707 [S14]. Jafari observed the object through the canopy as an intensely bright diamond shape strobing red, green, orange, and blue light so brilliant he could not resolve any physical body [S14]. As he closed in, the object executed a series of sudden angular jumps — reportedly 10 degrees to the right, then twice more the same amount, covering approximately 26 miles in under a second [S7]. Jafari accelerated to Mach 1 and beyond, but the object accelerated to maintain a constant 45 km standoff distance, confirmed simultaneously by ground radar [S12][S13]. At this point a smaller, round luminous object — estimated at roughly half to a third the apparent diameter of the moon — separated from the primary object and moved directly toward the F-4 at high speed [S13][S14]. Jafari attempted to fire an AIM-9 Sidewinder heat-seeking missile; the moment he tried to lock on, his fire-control console and all communications (radio and intercom) became inoperable [S13][S14]. He initiated a hard banking dive to evade, but the smaller object matched his manoeuvre and continued to pursue [S13]. After Jafari broke off evasion, the smaller object reversed course and rejoined the primary UFO [S12].

A second small object then separated from the primary UFO, descended, and apparently landed — or at least touched down — on a dry lake bed southwest of Tehran [S12]. General Yousefi, still observing from his balcony, witnessed what he described as communication between the primary "mothership" and the landed smaller object, with light connecting the two [S5]. The F-4 followed it down; as Jafari descended toward the light source on the ground, the light extinguished and he lost visual contact [S12]. Simultaneously, a separate UFO appeared to follow the F-4 as it subsequently approached the runway for landing, and a civil airliner in the area experienced communications failure — though its crew reported no visual sighting [S1][S5]. At dawn, the F-4 crew was flown by helicopter to the suspected landing site on the dry lake bed. Nothing anomalous was found at the exact site; however, circling westward, crew members picked up a strong beeper signal that peaked near a small house with a garden [S1][S5]. When they landed and questioned the occupants, the residents confirmed hearing a loud noise and seeing a very bright light like lightning during the night [S5].

Witness accounts

Hossain Perouzi (Mehrabad Airport night supervisor) — observed the primary object from the tower terrace with binoculars at approximately 23:15 on 18 September. He described it in detail: "Suddenly I saw it. It was rectangular in shape, probably seven to eight meters long and about two meters wide. From later observations I made, I would say it was probably cylindrical. The two ends were pulsating with a whitish blue color. Around the mid-section of the cylinder there was this small red light that kept going around in a circle... I was amazed. I didn't know what to think. There definitely was a very strange object there in the sky right over Tehran." [S4]

General Nader Yousefi (Base Operations Commander, IIAF) — authorised the scramble after observing the object from the balcony of his Tehran residence. In a television interview he recalled: "I put down my phone [with the Control Tower] and I ran to my balcony to see if I can see that object. I saw a big star among the other stars, which i[s larger and brighter]..." He also described witnessing what appeared to be the landing of a smaller sub-object and an apparent exchange of light between it and the main object: "He went down and landed on the ground and now it is a communication between the mothership and that small flying object, and it shows the lights between those two is connected." [S5][S6][S11]

Lt. General Azarbarzin (Deputy Commander-in-Chief of Operations, IIAF) — confirmed in a 1977 interview the electromagnetic effects on both F-4s: "That is true. They both were scrambled and they locked on the target but they received a very strong jamming. And then they lost almost every avionics system they had on the airplane... The jets couldn't fire their missiles because they had very strong jamming... this technology it [UFO] was using for jamming was something we haven't had before and we don't have it. It doesn't exist because it was a very wide band and could jam different bands, different frequencies at the same time. It's very unusual." [S6][S11]

Squadron Commander Parviz Jafari (second F-4 pilot) — pilot of the second F-4, recounted in subsequent interviews and public appearances that at Mach 1 the UFO instantaneously jumped approximately 26 miles in under a second [S7]. When the small sub-object detached and approached his aircraft, he attempted to engage with weapons but was immediately disabled: all instruments, including targeting and radio, failed simultaneously [S7]. He stated he had mentally prepared to eject if the object came within two miles of him [S7].

Ground residents near the dry lake bed — when questioned by the F-4 crew the following morning, reported: "a loud noise and a very bright light like lightning" during the night [S1][S5].

MIJI Quarterly (1978 classified U.S. military journal) — the anonymous author who wrote about the case prefaced the article with: "Sometime in his career, each pilot can expect to encounter strange, unusual happenings which will never be adequately or entirely explained by logic or subsequent investigation. The following article recounts such an episode as reported…" [S1][S8]

Physical / sensor evidence

Radar confirmation: The second F-4's onboard radar acquired the primary UFO at approximately 27 nautical miles and recorded a return consistent in size with a Boeing 707 commercial airliner [S14]. Ground radar at Mehrabad simultaneously tracked the object and confirmed that the UFO accelerated to maintain a constant 45 km standoff from the pursuing jet, corroborating the pilot's visual account [S12][S13].

Electromagnetic interference (EM effects): Both F-4 crews experienced sudden, total loss of UHF communications, intercom, and flight instrumentation at close approach distances — approximately 25 nautical miles for the first aircraft, and a similar range for the second [S3][S4][S12][S13]. Critically, the effect was directional and reversible: systems restored immediately when the aircraft turned away from the object [S3][S8]. The second F-4 additionally experienced weapons-system lockout — fire-control panel inoperative — precisely at the moment the pilot attempted to lock an AIM-9 missile on the approaching sub-object [S13][S14]. Lt. General Azarbarzin characterised the jamming signal as operating across multiple frequency bands simultaneously, unlike any known technology in either Iranian or American inventories at the time [S6][S11].

Civil aviation impact: A commercial airliner in the vicinity simultaneously experienced communications failure, though its crew made no visual sighting, suggesting the EM effect extended beyond the military aircraft [S1][S5].

Ground trace / beeper signal: The daylight helicopter sweep of the apparent landing site on the dry lake bed yielded no visible physical trace. However, crew members detected a strong, anomalous beeper (emergency locator) signal that peaked near a small house with a garden to the west of the primary landing zone [S1][S5]. The source of this signal has never been publicly identified, and follow-up information promised by the Attaché Office was not subsequently released [S1].

Radiation survey: The Defense Attaché's office noted that the landing area was checked for possible radiation, but the results were not released in available declassified documents [S1][S5].

Visual observation: Multiple independent observers — civilian callers, airport supervisor Perouzi with binoculars, General Yousefi from his balcony, and two separate trained military flight crews — all reported luminous phenomena consistent across accounts: bright object visible at extreme range (70 miles), multicoloured strobing lights, and sub-objects separating and returning to a primary craft [S3][S6][S7][S14].

Investigations

U.S. Defense Attaché Office (DAO), Tehran: The primary official investigation was conducted by the U.S. Defense Attaché at the American Embassy in Tehran, who compiled a detailed Memorandum for Record based on Iranian military sources and his own office's follow-up [S3]. This document was disseminated at the highest levels of the U.S. government — simultaneously sent to the Defense Intelligence Agency (DIA), the White House, the Central Intelligence Agency (CIA), the National Security Agency (NSA), the Joint Chiefs of Staff, the Secretary of the Air Force, the Secretary of Defense, and the Secretary of State [S3].

Defense Intelligence Agency (DIA): The DIA received the DAO memorandum and assessed the case formally. Their evaluation, widely quoted in subsequent UFO literature, rated it: "an outstanding report. This case is a classic which meets all the criteria necessary for a study of a UFO phenomenon." The DIA further noted that "an inordinate amount of maneuverability was displayed by the UFOs." [S12] This DIA assessment is among the most frequently cited official validations of a UFO case in any declassified U.S. government document.

MIJI Quarterly (1978): A classified U.S. military journal, MIJI Quarterly (Meaconing, Intrusion, Jamming, and Interference), published an account of the incident in 1978, treating it as an extraordinary case of electronic warfare/interference against military aircraft [S1][S8]. The journal's framing — from the perspective of avionics and electronic countermeasures — implicitly treated the EM effects as real and significant.

Imperial Iranian Air Force (IIAF): Senior Iranian Air Force officers, including General Yousefi and Lt. General Azarbarzin, conducted their own internal reviews and gave public and recorded interviews confirming the facts [S6][S11]. The Iranian military's position was that the incident was genuine and unexplained by known technology.

No USAF Blue Book involvement: The incident occurred after Project Blue Book was closed (1969), and therefore fell outside the formal Air Force UFO investigation program. It was handled instead through intelligence channels (DIA, NSA, DAO).

Hypotheses & explanations

1. Unknown advanced technology (aerospace/military)

  • Pro: Simultaneous radar tracking, multiple trained military witnesses, wide-band multi-frequency jamming beyond declared state-of-the-art, instantaneous large-displacement manoeuvres at Mach speeds, sub-object deployment and recovery — collectively difficult to attribute to any 1976-era known system.
  • Con: The Cold War context means advanced experimental aircraft (Soviet or American) cannot be entirely ruled out; however, no aircraft programme of the era is known to match the performance or EM characteristics described.

2. Astronomical misidentification (Jupiter / bright star)

  • Pro: Several early investigations and sceptics have suggested that the initial civilian sightings and possibly the command-post observation were of the planet Jupiter or a bright star, which was near the horizon and might have appeared unusually large.
  • Con: This hypothesis does not account for the radar returns, the sub-object separations observed visually and tracked on instruments, the EM effects on aircraft avionics, the beeper signal at the ground site, or the testimony of multiple trained pilots who made close-range observations at high speed.

3. Plasma / electromagnetic atmospheric phenomenon

  • Pro: Ball-lightning and related plasma phenomena can produce bright lights, multicoloured emissions, and may theoretically interfere with electronics.
  • Con: No known plasma phenomenon sustains for hours, tracks aircraft at Mach speeds, maintains a fixed standoff distance, deploys and recovers sub-objects, or produces the documented radar returns.

4. Extraterrestrial vehicle

  • Pro: The performance envelope — instantaneous acceleration, multi-Mach speeds, precise standoff maintenance, sub-object deployment, targeted wide-band EM suppression — exceeds any documented human technology of the era. The DIA itself acknowledged the case as a genuine UFO phenomenon.
  • Con: No physical artefact was recovered. The beeper signal source was never identified or disclosed. Extraordinary claims require extraordinary evidence, and despite the high quality of witness testimony, instrumental data remains limited to radar tracks and reported avionics failures.

5. Psychological / perceptual factors (cascade effect)

  • Pro: Mass-sighting events can involve social suggestion; once a bright light is reported as a UFO, observers may interpret subsequent ordinary stimuli anomalously.
  • Con: This does not explain independently corroborated radar data, the systematic and directional avionics failures, the weapons-system lockout, or the sub-object separation events described by trained aviators.

Resolution / official position

No official body has provided a satisfactory conventional explanation for the 1976 Tehran incident. The U.S. Defense Intelligence Agency's assessment remains the most authoritative public statement: the case is "a classic which meets all the criteria necessary for a study of a UFO phenomenon" and "an inordinate amount of maneuverability was displayed by the UFOs" [S12]. The incident predates the establishment of AARO (All-domain Anomaly Resolution Office, 2022), which has not publicly addressed it. Project Blue Book was closed before the incident occurred. The IIAF senior officers who investigated internally never attributed the event to any known aircraft or natural phenomenon [S6][S11]. The case is officially unresolved.

The promise of additional information from the U.S. Defense Attaché's office — particularly regarding the beeper signal source and the radiation survey results — was never fulfilled in released documents [S1][S5], leaving open the question of whether further classified material exists.

Cultural impact / aftermath

The Tehran incident achieved lasting status as one of the most credible military-pilot UFO cases on record, cited repeatedly across declassified-document compilations and UFO research literature. It appears in the Rockefeller Briefing Document [S4][S5][S6] — a 1995 summary prepared for Laurance Rockefeller's initiative to brief the Clinton White House on the UFO subject — as one of a small number of benchmark cases. It is also reproduced and analysed in the Disclosure Project Briefing Document compiled by Dr. Steven Greer [S3][S8], which was distributed to members of Congress and senior officials around 2001.

Squadron Commander Parviz Jafari became the most publicly prominent of the witnesses, giving interviews and appearing at UFO conferences worldwide for decades, including testimony before the National Press Club in 2007. His account has been widely disseminated in documentary films and online video [S7][S9][S10].

The case is regularly cited in discussions of UAP policy reform as an example of a well-documented, multi-witness, multi-sensor military encounter that received serious U.S. government attention but was never publicly resolved. The MIJI Quarterly publication [S1][S8] is particularly notable as evidence that the U.S. military treated the EM-warfare aspects of the incident as operationally significant.

Related cases

  • 1952 Washington D.C. UFO flap — mass radar/visual sightings over restricted airspace, F-94 intercepts, similar EM ambiguity
  • 1981 Rendlesham Forest incident — multi-night military encounter with physical ground traces, EM effects, and multiple witness tiers
  • 1986 Japan Air Lines Flight 1628 — commercial pilot encounter with large unidentified objects tracked on ground radar, sustained over extended duration
  • 2004 USS Nimitz "Tic Tac" incident — U.S. Navy F/A-18 intercept of anomalous object with radar confirmation, instantaneous manoeuvre characteristics, and avionics anomalies; structurally the closest modern analogue
  • 1968 Minot AFB B-52 incident — U.S. Air Force bomber with radar and visual UFO encounter involving temporary communications disruption
  • General pattern of military-interceptor EM cases — the Tehran incident is frequently grouped with a class of encounters where military jets experience systematic avionics failures attributed to proximity to an unidentified object [S2]

WAR.GOV/PURSUE Release 01 — COMETA package note

Release 01 row 19, represented in WAR.GOV UFOs and Defense, contains a NASA-labeled PDF copy of the COMETA report package. Its Tehran section summarizes the 18–19 September 1976 incident, the FOIA/DIA report context, multiple witness categories, communications/instrument effects, and the DIA "classic" assessment. This is useful secondary-source provenance only: the page should still rely on the original DIA/FOIA/primary records for case claims, and the 7 graph CANDIDATE_CROSSLINK relationships tied to Tehran remain needs_human_review / not_a_finding until exact Black Vault/document-page matching is done. [S15]

Sources cited

  1. [S1] TextChunk · archive_org_collections — UAP & Antigravity Research Document Index — High Strangeness — Rockefeller Briefing Document · https://archive.org/details/uap_antigravity_high_strangeness_index_20260421-043548 (excerpt: daytime helicopter investigation, beeper signal, ground witnesses, MIJI Quarterly reference)
  2. [S2] Claim · extraction — online commentary noting the Tehran incident as an instance of total instrument failure during UFO intercept
  3. [S3] TextChunk · archive_org_collections — Disclosure Project Briefing Document (Greer) · https://archive.org/details/DisclosureProjectBriefingDocument (excerpt: DAO report distribution list, first F-4 scramble narrative)
  4. [S4] TextChunk · archive_org_collections — UAP & Antigravity Research Document Index — High Strangeness — Rockefeller Briefing Document · https://archive.org/details/uap_antigravity_high_strangeness_index_20260421-043548 (excerpt: Perouzi binocular observation, physical object description, timeline from 22:30 onward)
  5. [S5] TextChunk · archive_org_collections — Rockefeller Briefing Document on UFOs — Rockefeller-Briefing-Document · https://archive.org/details/rockefeller-briefing-document (excerpt: General Yousefi balcony observation, civil airliner comms failure, ground investigation and beeper signal)
  6. [S6] TextChunk · archive_org_collections — Rockefeller Briefing Document on UFOs — Rockefeller-Briefing-Document · https://archive.org/details/rockefeller-briefing-document (excerpt: Lt. General Azarbarzin 1977 interview, both F-4s jammed, wide-band frequency jamming)
  7. [S7] TextChunk · extraction — 05-The First Commercial Flight Grounded Due to UFOs.txt (excerpt: Jafari's account — instantaneous 26-mile jump, sub-object approach, weapons/instrument failure)
  8. [S8] TextChunk · archive_org_collections — Disclosure Project Briefing Document (Greer) · https://archive.org/details/DisclosureProjectBriefingDocument (excerpt: MIJI Quarterly prefatory remark; first F-4 instrumentation loss and recovery)
  9. [S9] Claim · extraction — statement identifying Jafari as one of two jets dispatched
  10. [S10] Claim · extraction — general reference to the Tehran incident in media context
  11. [S11] TextChunk · archive_org_collections — UAP & Antigravity Research Document Index — High Strangeness — Rockefeller Briefing Document · https://archive.org/details/uap_antigravity_high_strangeness_index_20260421-043548 (excerpt: Azarbarzin interview, General Yousefi description)
  12. [S12] TextChunk · extraction — maj2.json (excerpt: DIA "outstanding report" / "classic" assessment; radar confirmation; sub-object landing and investigation)
  13. [S13] TextChunk · archive_org_collections — MAJESTIC Documents corpus — cometa_part1 · https://archive.org/details/MajesticDocuments (excerpt: COMETA report summary of both F-4 intercepts, fire-control lockout, sub-object pursuit and return)
  14. [S14] Document · richgel_catalogs — Eberhart Encyclopedia of UFO References — entry 5337 (named crew members: Capt. Aziz Khani, 1st Lt. Hossein Shokri, Sqn. Cmdr. Parviz Jafari, 1st Lt. Jalal Damirian; Shahrokhi / Hamadan Airbase; radar return; AIM-9 lockout attempt)
  15. [S15] Document / source pack — WAR.GOV/PURSUE Release 01 row 19, 255_413270_UFO's_and_Defense_What_Should_we_Prepare_For; generated source pack /home/exor/ufo-ingest/docs/wiki-source-packs/war-gov/ufos-and-defense.json · https://www.war.gov/medialink/ufo/release_1/255_413270_ufo's_and_defense_what_should_we_prepare_for.pdf

Open questions

  1. Beeper signal origin: What was the source of the strong emergency locator / beeper signal detected near the house with the garden west of the dry lake bed? The Defense Attaché's office stated follow-up information would be released but none has been publicly found. Are there still-classified annexes to the DAO memorandum?

  2. Radiation survey results: The Attaché's office confirmed that the landing-area ground was checked for radiation. Those results have not appeared in released documents. What was found, if anything?

  3. MIJI Quarterly full article: The 1978 MIJI Quarterly piece is described only in excerpt. Has it been declassified in full? Does it contain additional technical analysis of the EM-jamming mechanism beyond what the DAO memo reported?

  4. Intelligence agency downstream reports: The DAO memorandum was disseminated to the CIA, NSA, White House, Joint Chiefs, and multiple Cabinet secretaries. What analysis, if any, did these agencies produce? FOIA requests to the NSA in particular have historically yielded heavily redacted results on this case.

  5. First F-4 crew (Khani/Shokri) testimony: While Jafari became a prominent public witness, the accounts of the first F-4 crew — Capt. Aziz Khani and 1st Lt. Hossein Shokri — are comparatively sparse in the public record. Did they give formal statements or interviews beyond the initial DAO debrief?

  6. Civil airliner identity: The aircraft that experienced communications failure during the event has never been publicly identified (airline, flight number, crew). Its crew's testimony could provide an additional independent sensor data point.

  7. Post-revolution document fate: Following the 1979 Iranian Revolution, IIAF records were reorganised under the Islamic Republic of Iran Air Force. What happened to the original Iranian military investigation files? Have any Iranian researchers or officials released domestic documentation?

  8. Sub-object physical nature: The "landed" object was approximately 12 feet (3.6 m) in diameter according to one source [S12], yet no trace was recovered at the dry lake bed. Was the dry lake bed subsequently examined by professional geophysicists or soil scientists? Did the search area include the house with the beeper signal?

  9. AARO historical case review: AARO was tasked by Congress with reviewing historical UAP cases. Has the Tehran incident been formally entered into AARO's historical database, and if so, what is its current assessed status?

  10. Wide-band jamming mechanism: Lt. General Azarbarzin stated the jamming technology was unknown and unlike anything in the Iranian or American arsenals in 1977 [S6][S11]. Has subsequent advancement in electronic warfare — broadband noise jamming, directed-energy weapons — produced a plausible conventional explanation for the avionics effects? Or do the parameters still exceed known state-of-the-art?