Noises heard at 41 seconds

[Hacker15e]

Originally Posted by germb747

Critical Engine Failure Speed (CEFS) is basically the speed at which it will take the same amount of runway to go as it would to stop (Critical Field Length). Anyone know the civilian equivalent of that speed?

In a similar thread over at APC a while back, I asked for civil equivalents of the USAF terminology I've been taught and got a couple weird responses:

http://www.airlinepilotforums.com/ai...ckrides-3.html

For example, one response was that CEFS is actually a speed to fly while airborne after losing an engine and continuing the takeoff (?).

Originally Posted by a 757 driver over at APC

the speed that you must fly if you lose the most critical engine on takeoff

So, there are definitely differences between what the USAF teaches and uses and what the civilian world teaches and uses. My experience is limited to two-engined aircraft, so there is a pretty simple set of three speeds we use for this discussion. I've always thought of them in terms of one being a max speed, one being a minimum speed, and one being an exact speed:

Originally Posted by Hacker15e in a post on APC

Decision Speed: The MINIMUM speed at which I can lose an engine, then continue the takeoff in the remaining runway distance (called MIN GO speed in the F-15E).

Refusal Speed: The MAXIMUM speed at which I can lose an engine, then STOP in the remaining runway distance (called MAX ABORT speed in the F-15E).

Critical Engine Failure Speed: THE speed at which I can lose an engine, then either takeoff OR stop in the remaining runway distance.

The strangest military/civilian difference I've seen is how I see the term "decision speed" tagged to V1 in several of the forums that are discussing this issue. Seems to me that V1 is the same as "refusal speed", but this may just be another area where terminology between the USAF and the civilian world differs. If that's the case, I can see some serious potential for negative transfer for former USAF pilots going on to fly for the airlines.

[kellwolf]

Originally Posted by wheelsup

A -200 takes around 2000'-3000' to actually bring to a stop for touchdown upon landing. I would think it could be stopped in that or less when aborting, especially because you are getting on the brakes and thrust reversers immediately.

Sure, it CAN be done, but when you're rotating while QUICKLY coming up on the TDZ for the opposite end of the runway, it gets the blood flowing. Just b/c it can be done doesn't mean I'm itching to do it.

[granlistillo]

Hacker,

The part 121 definition for v1 would be your Critical Engine Failure Speed.

IE the max speed at which it can reach and be stopped in the ASD.

and

the min speed following a CE failure where it can continue the takeoff with the obstacle clearance requirements being met.

Both criteria have to be met. It may or may not resemble a balanced field condition, and it will be above vmcg. So below it, you abort and above it you go.

[SmoothLanderJ]

Originally Posted by SteveC

I'm even of the opinion that, at least in the Lears and Citations that I fly, it's better to get rid of the 80 knot decision mantra as well. We typically only have a short time between the 80 knots and V1 calls anyway, so I say forget about that "after 80 knots we'll only abort for loss of engine, engine fire, loss of directional control, or T/R deployment" stuff. I brief that we'll abort for anything before V1, because by the time I decide if that blinking light I see out of the corner of my eye is just a generator failure, or the first indication of an engine that's eating itself up, I'm probably already past V1. Others might make a different decision based on the characteristics of their airframes, but that's the way I approach it in the airplanes that I command.

Great thread and info. I also 100% agree with this. My takeoff breif is JUST like this.

[Baronman]

Originally Posted by SmoothLanderJ

Great thread and info. I also 100% agree with this. My takeoff breif is JUST like this.

Remember, he's in a Citation/Lear with V1 being fairly close to 80kts.

At the airline you fly at do the FOs perform the aborts? I ask because at many airlines it is the captains call and also he/she who performs the abort procedure.

Additionally, you fly a pretty modern aircraft, does the plane inhibit many of the warnings at high speeds? I know my aircraft inhibits certain messages at V1 minus a certain speed.

Have you ever had a spurious message go off above 80kts? I've had a bag door indication before V1 and continued. Aborting at 115kts would have been much riskier than continuing. In my head it wasn't a difficult choice because it didn't fall into a fire, power loss, directional control issue. I looked, the message wasn't one of those, I said "Continue" and that was it.

Sorry, I guess I'm just thinking that if someone briefed me that they're going to abort for anything below V1, we'd chat about it. There are just too many runways where we'd be aborting with a few thousand feet remaining for non emergency items that would be easily handled airborne.

[WalterSobchak]

For us it is CA's call on the abort. After we set the power CA has his hand on the power levers. The Saab also has a take off inhibit which limits the amount of erroneous annuciator. I brief most of my FO's that we will only abort for engine fire, failure, and controllablity issues. Saab is part 25 certified and you have TLR data that guarantee's your performance if you follow the procedures layed out(configuration, #'s etc.). However if you do have a structural failure you have to become a pilot and take what ever action you feel is necessary. For and engine failure at/after V1 we are flying period.

[TUCKnTRUCK]

As it would go...

" Any problems or warnings below V1, pilot noticing bring it to my attention. It will be my decision to continue or abort. If I do abort, it will be "MY Controls, ABORT ABORT ABORT" You coordinate with ATC, If it is significant we will stop on the runway, otherwise take it clear and run the checklists. Engine Failure before V1 stop on the Runway, After V1, standard * Profile Memory items at 1000 feet. Bring it back here and call it a day."

Can't think of many reasons why I would want to abort past V1 unless i left the control lock in

Used to make an 80kt brief... pertaining to RKD, and "poor" reported braking action. The other 1900 guys know why RKD got that

I will be interested to see exactly what happened though.

[germb747]

Originally Posted by Hacker15e

In a similar thread over at APC a while back, I asked for civil equivalents of the USAF terminology I've been taught and got a couple weird responses:

http://www.airlinepilotforums.com/ai...ckrides-3.html

For example, one response was that CEFS is actually a speed to fly while airborne after losing an engine and continuing the takeoff (?).



So, there are definitely differences between what the USAF teaches and uses and what the civilian world teaches and uses. My experience is limited to two-engined aircraft, so there is a pretty simple set of three speeds we use for this discussion. I've always thought of them in terms of one being a max speed, one being a minimum speed, and one being an exact speed:



The strangest military/civilian difference I've seen is how I see the term "decision speed" tagged to V1 in several of the forums that are discussing this issue. Seems to me that V1 is the same as "refusal speed", but this may just be another area where terminology between the USAF and the civilian world differs. If that's the case, I can see some serious potential for negative transfer for former USAF pilots going on to fly for the airlines.

There's the Air Force way, and then there's the everybody else way; why they always have to be different, who knows, but it can be a pain in the arse to keep the two distinct when you do both. In any event, I'll be furloughed in a few days anyway so looks like I'm back to the military way!

[gtpilot]

Originally Posted by kellwolf

Anyone that uses flex thrust on a CRJ on a short runway has had this thought, I know I have:

"Holy crap. That's all the runway that's left at V1?"

Was just thinking that coming out of Norfolk yesterday.

As for Lear Jets, it's still situational. With less than 5000' runways in 24s, 25s and 35s, there's no way you'd abort after 80 knots - V1 is only a second or two away at 110-120 knots. Over 5000' the thing can get airborne and land in that distance but your decision has to be instant because of how quickly you accelerate - even on a single engine. Again, a good take-off briefing for the situation would cover it well.

[Flyvne]

Originally Posted by Orange Anchor

way back when I was in the USAF we had 'minimum acceleration checks' which have never been used in the airlines or gen av to my knowledge. However, I began timing takeoff and all things being equal, from time of application of takeoff thrust (including using reduced thrust when applicable), you are rotating after about :30 seconds. If you go beyond that, you are heavy, it is hot, it is high, the runway is contaminated or a combination of all. At DIA and ABQ it was not unusual to have a takeoff roll of :45 seconds or greater.

The question is.. why the abort after V1.

Everybody... look at were the skid marks begin... I think I saw them start near the end of the touchdown zone (less then 2,000 feet down the runway). SO, if it took me 41 seconds to get that far, I think I might abort because I am not getting enough thrust.

41 seconds must be from when they appied power to taxi onto the runway for takeoff. I don't think they were above V1....