B-2 Crash - Guam

[tonker]

As per the title, no sound, second aircraft.


http://www.liveleak.com/view?i=f6d_1212714828

[cornish-stormrider]

Looks like the crew tried for quite a while before they banged out!!

I would have said goodbye when it dropped at the start of failure......

Any guesses on the cause..??

It was good to know the crew made it out ok, as always.

[nacluv]

Brave indeed, hanging around as long as they did.

Two thoughts -
1. Cameraman needs some serious training...
2. Shouldn't the squillions of $ of avionics and flight control processors have prevented the thing getting into that shape in the first place? Looked to me like it all started to go wrong at rotation. It was well before the point on the runway that the previous a/c nosed up. Then a high aoa immediately following. Software?

[Mike51]

http://www.acc.af.mil/accspecialreports/b-2accidentinvestigationboard.asp

[Madbob]

Good job the crew didn't land in that fireball :ok: Lucky chaps me thinks, they could have been toast. :D

MB

[barnstormer1968]

To avoid sounding ghoulish, my first concern is that both crew are OK, and I am always stunned at just how effective ejector seats can be, even when used at such low altitudes (thinking back to early B52's and Starfighters), and ground speeds.

While it also struck me just how poor the cameraman/woman was, I guess they didn't have any idea of what they were about to film.

So If I can assume that even at the high AOA this aircraft found itself in, the large wing area generates high lift, to me it still looks like a B2 has quite a fair amount of thrust to keep it flying for as long as it did (in some ways akin to the infamous F100 sabre dance)

Two questions arise from watching this clip:
How long did it take the crew to think to themselves that they may be in for a serious talking to (after throwing away such an expensive and rare asset), And that not everyone (thinking accountants here) will be just happy they are OK.

Secondly, what could any pilot do with any fin less, and fly by wire aircraft in such a similar position, where the aircraft is yawing so much, and with no real altitude to correct this (I say fly by wire, as the aircraft may be doing whatever it feels, depending on software constraints)

Barnstormer 1968

[Farmer 1]

Cameraman needs some serious training...


I suspect it's a remotely operated camera, hardly ideal for smooth, steady control of movement.

[CHINOOKER]

With regard the "poor camerawork".the video footage is most probably taken with a remote video camera,operated by a joystick,much the same as your local CCTV in shopping centres etc.
My only assumption to this is that it may be "common practise" for such a/c to be videoed in case of bits of the carbon fibre fuselage/wings etc decide to break off etc...as happened several times on the F117 stealth fighter!!

Seems the crew did the best they could,but in reading the report,the odds were stacked against them.....Good to see they got out though!

[wclark1238]

Aside from some type of major systems/software failure the only thing that comes to my mind is some kind of wake vortex incident. The way that the angle of attack increases so quickly just after rotation might be attributable to a disturbance in the airflow over the wing?

I've not bothered to look to see what the interval was between the first aircraft and the second but it didn't seem to be very long. As far as I recall the minimum interval for a MITO is supposed to be 60 seconds - certainly was something like that in my days whilst maintaining B-52s (at Andersen Air Force Base on Guam funnily enough - good to see the place again although not in the best of circumstances :uhoh:).

On edit - clearly, now having read the report into this crash, it had nothing to do with any wake vortices :\

[Brian Abraham]

The fire, which was reported shortly after takeoff, was followed by an uncommanded and uncontrollable roll.

Chief of Air Combat Command said in an article AW&ST "aircraft rotated early, rotated excessively, stalled and dragged the left wing tip". C of G is maintained by transferring fuel between fore and aft tanks and article questions if malfunctioning or mis-setting of system may play a role.

[brickhistory]

The B-2 joke is that upon first squeezing the ejection handle(s), a video of the Air Force Chief of Staff appears on the main MFD saying, "Oh no you don't. Try harder."

[Ex Douglas Driver]

http://www.acc.af.mil/media/archives/story.asp?id=123101589

B-2 ACCIDENT REPORT RELEASED

Release Number: 020608

6/5/2008 - LANGLEY AIR FORCE BASE, Va. -- Distorted data introduced by a B-2 Spirit's air data system skewed information entering the bomber's flight control computers ultimately causing the crash of the aircraft on takeoff at Andersen Air Force Base, Guam, Feb. 23, according to an Air Combat Command accident investigation report released today.

Moisture in the aircraft's Port Transducer Units during air data calibration distorted the information in the bomber's air data system, causing the flight control computers to calculate an inaccurate airspeed and a negative angle of attack upon takeoff. According to the report, this caused an, "uncommanded 30 degree nose-high pitch-up on takeoff, causing the aircraft to stall and its subsequent crash."

Moisture in the PTUs, inaccurate airspeed, a negative AOA calculation and low altitude/low airspeed are substantially contributing factors in this mishap. Another substantially contributing factor was the ineffective communication of critical information regarding a suggested technique of turning on pitot heat in order to remove moisture from the PTUs prior to performing an air data calibration.

The pilot received minor injuries, and the co-pilot received a spinal compression fracture during ejection. He was treated at Tripler Army Medical Center, Hawaii, and released. The aircraft was assigned to the 509th Bomb Wing at Whiteman Air Force Base, Mo.

The cost of the lost aircraft is about $1.4 billion.

[Marcel_MPH]

Recently the footage showing a B-2 crash at Andersen Air Force Base, Guam.

Footage can be found here

http://www.dutchops.com/Interesting/USAF_B2CRASH.htm

[Airbubba]

Air Force: Sensor moisture caused 1st B-2 crash
By JAYMES SONG – 14 hours ago

HICKAM AIR FORCE BASE, Hawaii (AP) — The Air Force on Thursday said the first crash of a B-2 stealth bomber was caused by moisture in sensors and estimated the loss of the aircraft at $1.4 billion.

The crash probably could have been avoided if knowledge of a technique to evaporate the moisture had been disseminated throughout the B-2 program, said Maj. Gen. Floyd L. Carpenter, who headed an accident investigation board.

The "Spirit of Kansas" abruptly pitched up, rolled and yawed to the left Feb. 23 before plunging to the ground at Andersen Air Force Base on the island of Guam. Both pilots ejected safely just after the left wing made contact with the ground in the first crash since the maiden B-2 flights nearly 20 years ago.

"It was just by the grace of God that they were safe, and the good (ejection) system," Carpenter said.

Water distorted preflight readings in three of the plane's 24 sensors, making the aircraft's control computer force the B-2 to pitch up on takeoff, resulting in a stall and subsequent crash...

Moisture in the pitot static system has caused many crashes over the years.

[Airbubba]

a video of the Air Force Chief of Staff appears on the main MFD saying, "Oh no you don't. Try harder."

Looks like he needed to try harder himself, he got fired yesterday...:)

[Ian Corrigible]

Cameraman needs some serious training...

It was still better camera work than the Bourne Ultimatum... :E

I/C

[glad rag]

So we know How it crashed but will we ever find out Why??

[advocatusDIABOLI]

I have to agree with an earlier poster; It looks like the 'rotate' occurs much earlier, but this could easily be due to different take off figures.

Still, I'm sure they didn't 'mean' to rotate to 30 nose up, so something must have gone T*ts Up! Overall, they look like they did their very best, and based on what the flight controls are doing :eek: they had their hands full!

Actually, contrary to earlier posters, I think they ejected only when they were sure they had really lost it (Quite right too!), it almost looked to me like they were actually trying to re-land / Abort ? But as always, it is really just a first glance impression.

Any heavy guys fancy a comment?

Regards,

Advo

PS: Glad they are OK(ish), but as always in these cases, it could have been so much worse. Money is just that.....Life is irreplaceble.

[Marcel_MPH]

Interesting. Looks like the pilot did a lot of effort to get the aircraft airborne after failing to take-off properly...

[nacluv]

So it's GIGO then. I suppose it's still software-related.

The late (but mercifully successful) ejection is, I would say, almost certainly due to the $$$$$$ figures involved. You wouldn't want to be seen to be abandoning that amount of cash without putting up a decent fight!

[patrickal]

Watching the video, it appears that they did not eject until the left wingtip came in contact with the ground. Talk about seconds from disaster. They must have waited till the AF Chief of Staff video finished and the credits ran.

What I really don't understand is how moisture contamination could cause this? What happens when they fly through rain? Guam may be hot and humid, but I would not call it a hostile environment. I know of several commercial accidents where instument ports were taped over or clogged with bird or insect nests, but you would think that an aircraft "hardened" for military use could handle moisture. Especially for $1.4 BILLION :ooh:

[Icare9]

OK, guys, it's my first post, so await all the usual scathing comments, but this aircraft actually has over 1,000 sorties of the 14,000 attributed to the B2 and apparently was on its last flight.....
Only too pleased that crew survived after staying with it until point of impact almost.....
Oh and by the way, congratulations to Henry Allingham, fear I started with the wine, women and whisky routine much later than him!!

[Shore Guy]

Here are the B-2 Guam reports (links bottom of page). Lack of turning on pitot heat for calibration cost "$1,407,006,920" (I'd like to hear about the last $920), and almost cost two guys their lives.


Wet sensors caused crash: B-2 Spirit bomber received 'distorted data'

By Brett Kelman
Pacific Daily News

Wet sensors and "distorted data" were responsible for the first-ever crash
of a B-2 Spirit bomber on Feb. 23 at Andersen Air Force base.

Maj. Gen. Floyd Carpenter, 8th Air Force vice commander and president of the
accident investigation board, explained the cause of the crash yesterday.

Carpenter said moisture on three of 24 sensors on the aircraft exterior
caused the flight computer to miscalculate the airspeed and pitch angle
needed for a successful takeoff.

"The airplane ... was in a normal takeoff attitude but the computer thought
otherwise," he said. "To correct it from what the computer thought was going
back toward the ground, it commanded flight control to put the nose up -- an
excessive nose-up attitude."

Carpenter said the pilots attempted to correct the error, but the aircraft
stalled and the left wing clipped the ground. The pilots were forced to
eject. One pilot was treated and released by Naval Hospital. The other
suffered a spinal compression fracture and was transferred to Tripler
Medical Center in Hawaii.

"It was just by the grace of God that they were saved and good systems,
obviously," Carpenter said. He said the pilots weren't to blame for the
crash.

The bomber crashed on the runway of Andersen Air Force Base about 10:30 a.m.
Feb. 23. Residents who were near Andersen could see the smoke, hear the
explosion and even smell the stink of burning fuel as it wafted over
northern Guam. The flames were estimated to be 2,000 degrees and reached 300
feet in height.

The crash was the first since the B-2 bomber was unveiled in 1988, according
to the Air Force.

Preventable

B-2 bombers are equipped with 500-degree heaters designed to dry moisture
off sensors, but Carpenter said the heaters weren't turned on.

Carpenter said moisture causes calibration errors so infrequently that the
use of the heaters wasn't part of pre-takeoff procedures. He said procedures
have been adjusted since the crash and aircraft are now subject to "much
more rigorous inspections."

"The issue of moisture isn't the problem, but when you do the calibration
with moisture in (the sensors), that's how you put the bad data in there.
Obviously, we've learned that lesson," he said.

Carpenter said another aircraft experienced a similar error at Andersen
weeks before, but the pilot was able to abort the takeoff. The aircraft was
recalibrated and took off successfully.

He said the moisture error was first documented in 2006. Information on how
to prevent it should have been circulated.

"Ineffective communication of that technique or standardization of that
procedure is a determining factor in this report," he said.

Carpenter was appointed to lead an investigation team of "experts from a
variety of Air Force specialties" two days after the crash. The
investigation lasted seven weeks and included 26 interviews, he said.

"Those that we interviewed ranged from the pilots who flew the mission that
day to maintenance airmen who worked on the aircraft, from the supervisory
personnel on duty that day to witnesses on the ground and first responders,"
he said.

Carpenter said he inspected the wreckage personally. Some wreckage still is
stored at Andersen, but it will be removed soon.

Carpenter said some parts of the bomber could be used for training purposes,
but the aircraft was lost. The Air Combat Command Public Affairs prices each
B-2 Spirit bomber at about $1.4 billion.

Busy skies

The bomber crash isn't the only aircraft incident at Andersen this year.


a.. On Feb. 12, a Navy EA-6B Prowler crashed into the water about 20 miles
northeast of Ritidian Point. Helicopters rescued three crew members within a
half-hour.


a.. On March 7, a B-1 bomber rolled into two emergency vehicles after making
an emergency landing at Andersen shortly after takeoff.

Yesterday, Carpenter said he hoped Guam's residents took comfort in the
number of planes overhead.

"I think the safety record of the United States Air Force and the systems
flying out of there made everyone feel pretty comfortable," he said. "In
fact, I would hopefully think it increases your feelings of safety that the
United States government is out there and flying in the skies."

Carpenter commended the residents of Guam and the local first responders
during his report. The Guam Fire Department and A.B. Won Pat Guam
International Airport Authority helped the Air Force in the hours after the
crash.

"The local community and first responders were quick to pitch in and offer
help and assistance. The support provided to us that day is indicative of
the tremendous relationship we have with the residents of Guam."


--------------------------------------------------------------------------------






Summary

http://www.guampdn.com/assets/pdf/M011005866.PDF

Factual

http://www.guampdn.com/assets/pdf/M011005966.PDF

[Ogre]

Someone posted a reply on Rumour Control about the cause being down to the Pitot heaters not being switched on. Sounds so simple but in an aircraft like the B2 that could be all it takes. The mission computer(s) rely on a lot of data, but as with any aircraft the simplest data is the most critical. The good old fashioned suck and blow instruments are the best, and with moisture in the pitot system the airflow would be corrupted. Airspeed, baro altitude, AOA etc are all calculated from the airflow around three things, the pitot probe, static vent and AOA probe. And believe me a mission computer derives a lot of things from these data sources.

Pitot heaters should be switched on before you take off, and kept on for the duration. A simple "ooops" but an important one.

P.S. it was an old liney trick to catch the new boys out, tell them the best way to check the heaters were working was to kiss the probe (the lips being very sensitive) but make sure the heaters had been on for a while before sending them off to check. Result - burned lips for the newbie and a chuckle for the old hands

Ogre

[ARINC]

Just remember to let the probes cool before putting the cover on.....otherwise it's time to break out the brillo pad :}

and anyway what happened to checking pitot static drain traps for moisture :suspect:

[Shore Guy]

Video of crash...

http://www.liveleak.com/view?i=f6d_1212714828

First aircraft departs normally, then......

[25thID]

Moisture in sensors caused the flight computer to set for takeoff which resulted in a 30 degree sudden pitch up. The bomber is heavily dependent on computer control for flight due to the unconventional design.

It was also stated in the final report that there was a means to make sure the sensors were moisture free prior to uploading the data to the flight computer. However, this method was only known by some aircrew and maintenance personnel. It was not disseminated to all air crew and maintenance personnel. Since the accident all personnel have been trained in how to get any moisture out of the sensors prior to upload to the flight computer.

I have a personal belief that this large oversight was one of the reasons for the termination of duty of the Air Force Chief of Staff and the Secretary of the Air force.

The termination of duty was officially listed as the oversight of flying a number of nuclear weapons on a aircraft across the US on a bomber that was supposed be carrying nothing. I was personally satisfied to see that high members of the command staff were held accountable.

So the US is out 1.4 billion dollars, but the crew is safe, I hope it never happens again.

[stilton]

This billion dollar aircraft doesn't have pitot heat switches :confused:

[pattern_is_full]

It has the switches (and 500-degree heaters) - they just got left out of the takeoff procedures manual.

So - hmmm - this crash took place a month AFTER the BA 777 at Heathrow - with more complete destruction of the evidence (blast/fire) - and the USAF has already released the report and updated procedures while Boeing, RR, BA etc. are still wuffling about?

:hmm:

[Brian Abraham]

they just got left out of the takeoff procedures manual
Nope. All explained here. My bolding. From http://www.flightglobal.com/articles/2008/06/06/224493/videos-b-2-crash-linked-to-moisture-maintenance-oversight.html

Moist air most likely caused the US Air Force to lose one of its prized Northrop Grumman B-2 bombers earlier this year, a loss calculated at $1.4 billion, the US Air Force reported on 5 June.

During a takeoff on a Guam runway on 23 February, moisture contamination on the fly-by-wire B-2’s air data sensors threw off the tailless bomber’s sensitive flight control system.

The onboard computer believed the bomber was pointed slightly downward on takeoff roll and rolling 10-12 knots faster than its actual speed.

These two errors set off a chain of events that caused the bomber to crash.

First, the faulty airspeed indication caused the bomber to depart the runway about 1,450ft sooner than normal. During the early rotation, the incorrect angle of attack data caused an uncommanded, 30-degree pitch-up. The bomber’s slow speed at this 1.6g-inducing angle caused the aircraft to stall, yawing until its left wingtip scraped the ground.

At that moment, the B-2’s two crewmembers ejected from the aircraft. The crewmember identified as “mishap pilot-2” in the USAF report pulled the ejection handle, although the first pilot also told investigators he knew it was time to “get out”.

In the next instant after the pilots ejected, the B-2 spun into the ground, ripping off the nose gear and left main landing gear. The second crewmember suffered a compressed spinal fracture during the ejection, but is expected to fully recover. The other crewmember was lightly injured.

The first crewmember attempted to recover the B-2 after the uncommanded pitch-up, but faced a perhaps impossible task with the low-speed and low-altitude conditions.

With no abnormal control inputs by the crewmembers, the USAF investigation focused on the aircraft’s maintenance procedures.

On a previous deployment, maintenance crews found that moisture could foul up sensors unless a special technique was performed. The technique involved heating a pitot tube to burn off moisture before the engine was started. Despite the severity of the problem, USAF investigators found that the technique was not widely communicated among the maintenance crews.

On the day of the crash, a maintainer performed an air data calibration without heating the pitot tube. Because the sensors were coated with moisture, the calibration actually drove transmitted latent errors into the flight control system, the USAF’s report says.

[airfoilmod]

Just after the emphatic Pitch up, notice the (apparent) beginning of a Roll to the Right, then Max Port Spoileron, which overcorrects and causes the unrecovered Roll left, followed by inboard starboard Flaperons, then Starboard Spoilerons, Though not Full. The A/C hit the ground at 90 degrees to RW heading left wingtip first in an entry to what the original Pilots (~1945) called "boomerang". The Flying Wing had two fatal attitudes, a "tumble" or somersault about the Span axis, and an unstalled spin, or "boomerang". These were evident in the early life of the B-2's ancestor, the Y-B 49. Without FBW, there is no B-2. This crash was, I think, untouched by Human Hands. Without a computer (functioning) it is an unflyable Beast, Thank God the Major and the Captain survived.

[Marcel_MPH]

In other words: Murphy's Law???

News and video @ www.dutchops.com

[wclark1238]

After engine start the crew noticed an error on the flight computer so maintenance 'redballed' out to the jet and did a reboot and recalibration. The results of this were satisfactory so the jet was cleared for take-off (long sortie back to home base after a 2 month deployment).

Unknown to all at the time, the original flight computer fault had been caused/triggered by moisture in some of the airspeed sensing ports. When maintenance went out and recalibrated the system the moisture affected ports had erroneous 'error correction' values uploaded because of the moisture present.

The proper fix for the initial problem probably would have been to simply turn on pitot heat which would have eliminated the water and almost certainly brought the readings back into normal range without any need for a maintenance intervention.

On takeoff roll, crew having turned on pitot heat as normal, the moisture present was caused to evaporate and the flight controls computer quickly recognised some anomalies and flagged an amber alert on the flight display but this was at a ground speed beyond that which the crew could abort the take-off. The alert cleared a few seconds after appearing but the aircraft was, at this point, virtually unflyable. Flight control computer detected a nose down attitude (resulting from the erroneous data from the airspeed ports that had seen recalibration) after rotation so it commanded additional nose up flight control movements which the crew fought against manfully but they were unable to return to controlled flight and wisely ejected.

It seems that the aircraft came to ground in relatively good shape and was largely in one piece but the fuel tanks were compromised and the resulting fire left Uncle Sam $1.4 billion down on the day.

[alph2z]

2 original videos from .mil site:
http://www.acc.af.mil/shared/media/document/AFD-080605-049.wmv

http://www.acc.af.mil/shared/media/document/AFD-080605-046.mpg

2 annimations:
http://www.acc.af.mil/shared/media/document/AFD-080605-050.wmv

http://www.acc.af.mil/shared/media/document/AFD-080605-051.wmv

Text 1 of 3:
http://www.acc.af.mil/shared/media/document/AFD-080605-054.pdf


Main page:
http://www.acc.af.mil/accspecialreports/b-2accidentinvestigationboard.asp
.

[SpringHeeledJack]

In case this hasn't been posted before....

B2 Crash Pics - First Photos of B2 Bomber Crash - Popular Mechanics (http://www.popularmechanics.com/science/air_space/4273248.html)


Safe flying


SHJ

[nacluv]

The most expensive slice of toast in history. Ouch.

[Ali Barber]

High tech aircraft and rain - not a good combination perhaps?

[GreenKnight121]

Would have been no problem if the known problem and its known "fix" had been made part of the standard test routine as well as the pre-flight check-list.

The pilots knew they had to heat the tube to get an accurate reading... why didn't the ground crew?

[Green Flash]

Er, pitot covers, anyone?:rolleyes:

[theron]

that video shows a great comparison, it really emphasises the differences... how much earlier on the runway the plane rotates as well as the very high pitch. thanks for sharing.