phlwookie

N113UW per http://www.avherald.com/h?article=471583da&opt=0

Details: http://www.airfleets.net/ficheapp/plane-a320-1141.htm

pa3lsvt

Cecily Tynan (meteorologist for 6ABC) had a segment during the coverage of US1702 on last night's 11 PM broadcast. She said that during the time window for the event the winds were cross-winds coming from NNW-ish and were more of a cross-wind rather than a headwind for 27L.

She outlined the maximum cross-wind rating for A320 takeoff and that the limits were well above actual conditions, including maximum gusts during the 6 PM - 7 PM window. (This is why I watched that channel - it was actual journalism with research and data, not just reading Twitter posts on the air.)

I arrived about 90 minutes before this event and the pilot had a heck of a time keeping the CRJ200 wings level on approach with all the gusting. It was certainly not an easy day to fly at PHL yesterday.

DaviddesJ

Really? Doesn't it seem more likely that he aborted takeoff due to some unrelated cause (e.g., engine problem) and then coming down hard blew the tire? The blown tire could be the root cause, but it seems more likely to have occurred later (since it's not at all surprising that coming down hard on the runway would blow the tire).

N830MH

Thanks! You did great job yesterday. I'm so grateful to save the life. Everyone is doing very well. You are very good witness. You saw what happened yesterday. They save the day.

No one who responsible for this. They did not change a new tires. They didn't do right. Something wasn't right. They did not check the tires. They have to make sure everything is okay. If the tire is good or bad. It was not their fault. No one who blamed tham! Every time they have change a new tires.

Cargojon

the day before wasn't much better. Gusting to 33 MPH according to the pilot ans our landing was pretty wavy...

phlwookie

All we know is that US has been very consistent in stating it was a tire issue that started the incident sequence, and all I'm saying is that I saw nothing to contradict that. This assertion has persisted today as well (such as in this report: http://abclocal.go.com/wpvi/story?se...cal&id=9465339).

A blown tire could have distributed debris to the engines, or the crew might not have known if or what the collateral damage was and elected to do a late abort, or the abort could have been complicated by a wind gust. Maybe the crew did an incredible job getting the plane back on the ground with contents intact - or maybe they did a horrible abort and they should never have gotten off the ground. We'll find out as the investigation plays out.

BoeingBoy

To add my answer to the question of when to abort and when to keep going...

In theory, the V1 speed is the go/no-go speed. Any problem before V1 and you abort, any problem after V1 and you continue the take-off since at that point it takes less runway to continue than to stop. The other relevant speeds are Vr (rotate to nose up attitude) and V2 (should be passing 50' and climbing).

I say "in theory" because judgement does enter into the decision - you certainly wouldn't want to try taking off if both engines quit just after V1, you'd want to apply full braking regardless of runway left because the airplane would start slowing down and have no chance of getting airborne, never mind actually flying around for an approach. Also entering into the judgement call is runway remaining. V1 is calculated assuming that is just long enough to get airborne as long as everything is normal. For a relatively short flight like PHL-FLL (with a plane capable of flying transcon) there could be a pretty good amount of runway 27L still available at V1 and Vr.

The apparent fact that the plane got airborne makes it sound like something happened after Vr - wind gusts could cause airspeed fluctuations but with normal acceleration after Vr that wouldn't make much difference unless the gust was appreciably greater than the base wind. Another place judgement enters the picture - if you're getting 10-20 kt fluctuations in airspeed during the takeoff roll don't be in a big hurry meeting V1/Vr standards. Delay both some to allow for possible gusts. Better too much speed than too little once airborne.

What happened between approaching V1 and being airborne? We'll have to wait for the NTSB investigation for that. It certainly appears that whatever happened, it caused the crew to change their mind (in that instant they had) about the ability of the plane to continue flying.

Just an example - PI had a 727 taking off on what was 14 at IAH at the time (now 15L) - 12,000' long with a normal takeoff using less than half. They experienced a turbine failure in the #1 engine just after Vr and elected to just pull the power back and land. As it turned out, turbine blades from #1 penetrated #2 and that engine could have quit at any time. The hydraulic system that retracts the gear/flaps uses engine driven pumps on #1 & #2 so they could have lost the ability to retract gear/flaps at any time. The 727-200 can't continue to fly on one engine with the gear down - in fact, gear down is the commit point for an approach to landing. There's no go-around capacity with the gear down - the ibw remaining engine will only take you to the crash site if you attempt a go-around. So their decision, made in that split second, could have prevented an off-airport crash with loss of life. That's the judgement that is always required when something goes wrong.

Jim

jdanton

So I took off to SFO about an hour before this happened--the wind didn't feel that bad. It was breezy when I walked into the airport, but it wasn't crazy windy like it was in the morning. Thankfully, everyone is ok.

phllax

Jim - the meterological conditions sound similar to what happened to Continental 1404 in Denver a few years ago, except this time they were at Vr. As you said above, with winds gusting as they were, would you hold her down for an extra 50 kts or so cushion to help in case you were hit by a microburst or cross-wind gust at Vr?

BoeingBoy

About half the wind gust - an extra 50 kts is an awful lot. For example, with wind blowing at 10 gusts to 50 that's only a 40 kt gust so add an extra 20 kts to Vr. It also helps that the airplane will fly well below any of the V speeds. Minimum unstick speed is part of the certification testing that all new plane designs go through - raise the nose to drag the tail on the runway (actually a wooden block attached to the tail) as soon as the elevator can exert enough force to do that, continue the acceleration and see at what speed the plane will lift off the runway. Something in the 80-100 kt range if pretty standard and that's at least 20 kts under Vr for a lightly loaded airplane.

A micro-burst is a very specific phenomenon and I've seen nothing to indicate that the factors that produce microbursts were present in PHL.

One thing I forgot to mention in the last post - gusts shouldn't cause the plane to be airborne early. With the leading edge flaps/slats extended the wing has a negative angle of attack and absolutely won't fly until a positive angle of attack is attained - it'll run off the end of the runway first no matter how much runway there is. Normal procedure is to apply a slight forward pressure on the controls (stick in the Airbus) for the purpose of ensuring that gusts won't cause the plane to get airborne early since the trim setting should be about right to start raising the nose about Vr.

Gusts do bring wing sweep into the picture since all transport airplanes are designed with some amount of wing sweep to decrease drag at higher mach numbers. With a quartering crosswind the upwind wing is closer to having a headwind than the downwind wing because of the sweep (in this case wind out of the NW while taking off to the west, the right wing is the upwind wing). That means that the right wing in this case would develop more lift when a positive angle of attack is reached and would tend to rise faster than the left. But again, this is as the plane is rotated to the initial climb attitude, not prior.

There is a phenomenon that can be present at airports along the downwind side of mountain ranges that is called a rotor wave and was initially blamed for a UA crash at Colorado Springs. As the wind flows over the mountain range, aerodynamics says that the wind will fill in the lower pressure area on the downwind side of the range, creating a rotor-like effect - the wind on the downwind side of the range rotates around a horizontal axis. The wave itself remains in place just on the downwind side of the range. In the case of the UA flight making an approach to the north, it was speculated that the left wing entered the downward portion of the rotor wave, causing a sudden roll to the left which in turn caused the nose to drop. The flight was close enough to the ground that there wasn't room to recover before impact.

This was several years before the US 737 crash at PIT, which was finally found to be a fault in the rudder actuator which caused the rudder to go to the mechanical stop (a rudder hardover) and consequently the plane rolled nearly inverted and the nose dropped to nearly straight down. Again, there wasn't sufficient altitude to recover and everyone on board perished. I don't know if the NTSB then reopened the UA crash or not. However, in somewhere like PHL there's nothing to cause a rotor wave strong enough to have much effect and at least the 737's had their rudder actuators fixed. It's never been reported as a problem on the Airbus.

Jim

phllax

Jim,

Thanks for all the technical Information. I remember a large article in maybe Time or Newsweek about the rotor being the likely initial cause of the COS accident. One last question, in instances of high sustained winds right on the nose on take off, can Vr ever be before V1 on a non-STOL aircraft, and on a runway with enoug length, like Denver's 12,000 and 16,000 foot runways?

Rectiffied

Hi, I came across this sight searching for REAL information. Finally someone is telling the truth!! I was on this flight. It was by far the scariest event in my life. The pilot spoke for 5 minutes before takeoff warning us of severe turbulence. I was in the back of the plane. As we started taking of there was a huge jerk to the left (I described it as trying to avoid a pot hole..but obviously a lot stronger) The plane then kicked into a higher speed, we hit another strong burst of turbulence as we were still going up, Then suddenly it felt as something just slammed us back down on the ground. We hit the ground and went back up and again it sounded like the plane hit it into a faster speed like he was trying to continue taking off and fight through whatever it was (my inital thought was wind) We then slammed the ground a second time. We were then on the ground and he was hitting the breaks as we were being rocked back and forth. (I was pretty much bracing for impact) After the plane came to stop, You could smell smoke from the tires but we could see and smell from the back window smoke. The pilot came on and said EVACUATE NOW. Chaos broke out, people were screaming, our attendant stood still in a panic and would not open the back door until we literally screamed and cursed at her to do so. I had to yell at people to leave their F**king bags, Stop grabbing your bags!, The attendant was still just standing in place. We had to wait for people to come hold our slide bc the wind was blowing it into the air. I was pushed from behind out. Thank god I landed on my feet, Other people were landing on each other and hitting the ground hard. We were in a field a lot longer than they are saying. Thank you for you account of the time the busses were dispatched. They then brought us into a room, gave some of us free alcohol but never assessed our conditions. I never heard a sorry or an explanation. They kept us for 3 hours, finally brought our bags and tried to get us out of there as fast as possible. I commend the pilot, but the attendants did not keep us calm or do their job, The airport kept us in freezing temperatures (many of us dressed for warm weather) for over an hour, and US AIR kept us in what I can only describe as a brainwashing room for 3 hours before releasing us with nothing but a See YA.

FAA1996

Thanks for the report, and welcome to FT; sorry about your experience, I'm surprised that they didn't treat you Bette, wonder if there will be compensation after the dust settles down?.... FAA1996

phlwookie

Thanks for your account, it's the most detailed I've seen from anyone on board thus far. Sorry you had to go through this and I hope you're doing OK now. As I noted, I was still shaking just from having observed it from 4,000 or so feet away for a while and I can't imagine what has been going through the heads of everyone on board since.

A couple comments:

• The huge jerk to the left might have been the tire blowing out that we've heard as the root cause. I've never experienced that as a passenger taking off in high wind conditions so I suspect that might have been the first event in the accident sequence, though BoeingBoy, our resident pilot in here, may have more to say on that.
• Whatever caused you to slam into the ground for the first impact is still a mystery to me. Do you recall whether there were variations in engine noise during the first liftoff? Such as power being cut back? There are quite a few possibilities - wind shear, other damage to the aircraft, human error from the cockpit, etc. Your plane got my full visual attention when I saw it beginning to descend just after getting airborne out of the corner of my eye, but I didn't see anything obvious that caused it to do that such as smoke or flame from an engine. I have not seen anything in the media describing either debris on the runway (e.g., something like tire rubber getting chewed up by an engine) or the tire marks on the runway, though I'm sure that will come out of the NTSB report eventually.
• The performance of the flight attendants appears to be very disappointing. You never know what people will do in an emergency - even if trained for it - until they're actually in one, but they needed to help here, not freeze up.
• Now that you mention it, I seem to recall a report (though I can't find it right now) stating that they were getting passengers off of the runway area about 30-40 minutes after the evacuation, but looking back at my own timeline the buses clearly didn't pass me until over an hour after the accident.
• We know that some folks headed to Ft Lauderdale later that evening, but some definitely did not as I saw a few being interviewed when I left the airport. I'm curious as to how many elected to go just 5 or so hours later.
• Has US provided any post-accident assistance or otherwise been in touch?

Once again thanks for your info and best wishes.

Staymates788

Wow... What a read! Glad to hear you (as well as the other passengers) are ok.

I have a question about the flight attendant frozen in panic... After seeing the picture of the plane, tail in the air, along with the slide, do you think maybe she didn't want to open the door because the slide wouldn't reach the ground?

As to serving alcohol, that just sounds bizare... I assume someone would be wanting to take your statement. I can't imagine that going well after a few drinks!