Forum: General

I get the press releases regularly, thought I'd share.

PRESS RELEASE -- Secretary of the Air Force, Directorate of Public Affairs

Release No. 0121045 - Jan 21, 2004

Thunderbirds Accident Report Released

LANGLEY AIR FORCE BASE, Va. - Pilot error caused a U.S. Air Force Thunderbirds F-16 aircraft to crash shortly after takeoff at an air show Sept. 14 at Mountain Home Air Force Base, Idaho.
The pilot ejected just before the aircraft impacted the ground.

According to the accident investigation board report released today, the pilot misinterpreted the altitude required to complete the "Split S" maneuver. He made his calculation based on an incorrect mean-sea-level altitude of the airfield. The pilot incorrectly climbed to 1,670 feet above ground level instead of 2,500 feet before initiating the pull down to the Split S maneuver.

When he realized something was wrong, the pilot put maximum back stick pressure and rolled slightly left to ensure the aircraft would impact away from the crowd should he have to eject. He ejected when the aircraft was 140 feet above ground -- just eight --tenths of a second prior to impact. He sustained only minor injuries from the ejection. There was no other damage to military or civilian property.

The aircraft, valued at about $20.4 million, was destroyed.

Also, the board determined other factors substantially contributed to creating the opportunity for the error including the requirement for demonstration pilots to convert mean sea level and above ground level altitudes and performing a maneuver with a limited margin of error.

For more information, contact the ACC Public Affairs office at (757) 764-5007 or e-mail acc.pam@langley.af.mil.

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Finally! They admit what most here have been speculating---pilot error.

For you pilots, why does the press release say he should have reached 2500 AGL at the apex of the split-s, or more appropriately, the reverse half cuban eight? I read in the F-16 Aerial Demonstration Manual (in the <a href="modules.php?op=modload&name=Downloads&file=index">downloads section</a>) that all vertical roll manuevers require a minimum 5000 AGL and target 6000 AGL apex. What explains the difference between 2500 and 5000 AGL---do the Thunderbirds do their manuevers twice as tight as everyone else?

Thanks!

See also the news article <a href="f-16_news_article842.html">Thunderbird crashes at Idaho air show</a>

... and the forum topic <a href="f-16_forum_viewtopic-t-126.html">Thunderbird Crash 14 Sep 2003</a>

and of course the <a href="PhotoGallery/album44/aby.mpg">in-cockpit video</a> of the crash</a> (4.1Mb)

I'm not a flight expert, just a casual observer, but it seems to me that this mistake is one that gets made alot in high performance flight. I personally have witnessed two airshow crashes (both at El Toro, one fatal, one amazingly not) where pilots have not gained enough altitude to complete their meneuvers. Is it just a matter of paying closer attention to your instruments and situational awareness or is there something more sinister lurking here?. . .

Complacency.

If the F-16 is about 50 ft. long, how does the report arrive at eject height of 140' AGL? The photos at my site don't bear this out. In fact, it looks to be HALF that...

Thunderbird 6 Eject/Crash photos at <a href="http://www.authphoto.com/maatbirds/tbpage.htm">http://www.authphoto.com</a>

Marc Auth
AUTH Photo
Boise, Idaho

Guessing they are basing it on RALT data stored in the CSFDR at the instant the ejection sequence was initiated (pulled the handle). Kevin can add more detail but there is a finite amount of time after the ring is pulled before the seat leaves the jet. During that time the jet continued to descend.

I for one am just glad that the driver and the spectators all went home on their own power!

Loader wrote:

I for one am just glad that the driver and the spectators all went home on their own power!

I agree. Hey it was only a Block 25. No big deal Twisted Evil

habu2, is probably correct. To decide when he initiated ejection look at the first movement of the canopy, not the seat. Seat separation occurred while the plane was already digging a trench so that is about 4 tenths of a second after the seat reached the sequence start point near the top of the rails. I'd have to either dig thru some manuals that I can't currently access or ask Mark to let us know if there is a delay or what the expected canopy separation time is. It probably is some 0.4 of a second for that. That would total to the 0.8 seconds as reported in the press release.

Kevin
The Ejection Site

Quote:

Hey it was only a Block 25

Ummm, Block 32 - a $20,000,000 deal

Block 25 = Block 32

Better to put on a show like that then to end up rusting at AMARC.

Canopy jettison times vary by airspeed. A 0/0 ejection will take approx 0.75 seconds for the canopy to jettison to the point of lanyard initiation of the M99 initiators (seat fires) a 600 KIAS ejection will take approx. 0.13 seconds for the same thing to happen.

mark, is the longer delay at 0/0 intended to give the canopy more time to clear the seat path?

habu2 wrote:

mark, is the longer delay at 0/0 intended to give the canopy more time to clear the seat path?

No, it is due to the airflow tearing the canopy off. In a 0-0 there is no airspeed so the canopy is removed purely by the thrust of the canopy jettison rockets pushing it. At 600kts the relative wind assists in the rapid removal.

Kevin
The Ejection Site

Forum: General

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