Citation Incident at Leeds
Paradise Lost I agree wholeheartedly with your general policy that 'post-V1, I'm getting airborne'.
I think one of the interesting points during my event was that I wasn't convinced that we could get airborne before running off the side of the runway. Although I was sure that the failure itself occurred prior to V1, with the delay in recognition, etc, it's quite possible that the abort was initiated beyond V1 but I can't be sure as the instruments were unreadable due to the vibration.
I also agree that having an extra criterion at 80kts in a light jet can be unnecessarily complicated, especially on a long runway. On a 'short' runway however, it may help to focus the mind on the 'go case' if one restricts the reasons for a 'STOP' call above a nominated speed (typically 70 or 80kts) to a short list (red lights, etc). I suppose it all comes down to how confident you are of the success of a Rejected Take-Off at a speed close to V1 under the prevailing conditions. On a long runway (as in my case), you have the comfort factor of knowing that you could stop for 'anything' up to V1 and stop relatively easily. On a short runway, you would be more likely to be 'go minded' for a minor failure, as you would be aware that the margin for error in accomplishing the RTO manoeuvre was much smaller. That's when a distinction between major and minor failures might be appropriate.
Bral I didn't know it was a tyre failure until I got out and had a look at the damage.
I suppose I could have started my post by saying, 'A few years ago I had sudden severe vibration, steering difficulties and unreadable instruments shortly before V1 in a CJ1, all of which led me to believe that I had some sort of tyre failure.' I was just trying to convey the essence of what happened in an economical way.
The shaking was so severe that I was actually concerned about structural damage. That, combined with the steering problem convinced me to reject. I didn't immediately try to decide whether it was a tyre deflation or failure; there were no 'lightning fast reflexes and abilities' (but thanks for the compliment anyway). I was simply trying to stay alive by avoiding going off the runway into the bundu at 100kts +.
I'm not sure that your statement is relevant to my post; Firstly, the symptoms appeared before V1; secondly, I wasn't sure that the aircraft would fly (subsequent viewing showed that the damage to the flaps, wing and tailplane was quite severe and there was a possibility of elevator jamming due to rubber fragments); and thirdly, I don't think that my actions would indicate that I ignored my training, nor that I am incapable of taking the concept of V1 onboard. I could have described another incident in a 737-400 when we got a momentary stick-shaker just as we got airborne. We continued and sorted it out before landing uneventfully.
I'm sorry if you feel that I'm trying to justify my decision with bullsh!t talk after the event. I welcome any constructive criticism and if anybody can explain to me that what I did was wrong, please go ahead. I'd be the first to admit that I've made some bum decisions during my career. I felt it would add to the debate to describe my experience and some of the thought processes. If you believe I made a mistake, I'll take it on the chin and try and learn from your opinions.
I do ask that you re-read my post first and you may see that we agree on the fundamentals!
Thanks for the input anyway!
Outside CAS I think you've hit the nail on the head. I've conducted (and been subject to) many recurrent checks in the aircraft and the sim, and it's true that for 'procedural checklist' training, the sim wins hands down. For stalls, steep turns, etc, the aircraft is better. I'm sure there is a difference in crew reactions if they have never seen the 'bells and lights' until they get an actual problem in the aircraft.
Eck
I think one of the interesting points during my event was that I wasn't convinced that we could get airborne before running off the side of the runway. Although I was sure that the failure itself occurred prior to V1, with the delay in recognition, etc, it's quite possible that the abort was initiated beyond V1 but I can't be sure as the instruments were unreadable due to the vibration.
I also agree that having an extra criterion at 80kts in a light jet can be unnecessarily complicated, especially on a long runway. On a 'short' runway however, it may help to focus the mind on the 'go case' if one restricts the reasons for a 'STOP' call above a nominated speed (typically 70 or 80kts) to a short list (red lights, etc). I suppose it all comes down to how confident you are of the success of a Rejected Take-Off at a speed close to V1 under the prevailing conditions. On a long runway (as in my case), you have the comfort factor of knowing that you could stop for 'anything' up to V1 and stop relatively easily. On a short runway, you would be more likely to be 'go minded' for a minor failure, as you would be aware that the margin for error in accomplishing the RTO manoeuvre was much smaller. That's when a distinction between major and minor failures might be appropriate.
Bral I didn't know it was a tyre failure until I got out and had a look at the damage.
I suppose I could have started my post by saying, 'A few years ago I had sudden severe vibration, steering difficulties and unreadable instruments shortly before V1 in a CJ1, all of which led me to believe that I had some sort of tyre failure.' I was just trying to convey the essence of what happened in an economical way.
The shaking was so severe that I was actually concerned about structural damage. That, combined with the steering problem convinced me to reject. I didn't immediately try to decide whether it was a tyre deflation or failure; there were no 'lightning fast reflexes and abilities' (but thanks for the compliment anyway). I was simply trying to stay alive by avoiding going off the runway into the bundu at 100kts +.
On a Perf A aircraft V1 is V1; unless the aircraft won't fly, you get airborne. I suspect there a few who are incapable on taking that onboard or think it better to ignore their training and justify their decisions with too much bullsh!talk after the event.
I'm sorry if you feel that I'm trying to justify my decision with bullsh!t talk after the event. I welcome any constructive criticism and if anybody can explain to me that what I did was wrong, please go ahead. I'd be the first to admit that I've made some bum decisions during my career. I felt it would add to the debate to describe my experience and some of the thought processes. If you believe I made a mistake, I'll take it on the chin and try and learn from your opinions.
I do ask that you re-read my post first and you may see that we agree on the fundamentals!
Thanks for the input anyway!
Outside CAS I think you've hit the nail on the head. I've conducted (and been subject to) many recurrent checks in the aircraft and the sim, and it's true that for 'procedural checklist' training, the sim wins hands down. For stalls, steep turns, etc, the aircraft is better. I'm sure there is a difference in crew reactions if they have never seen the 'bells and lights' until they get an actual problem in the aircraft.
Eck
Outside CAS, I think you have raised a very valid point. If you have not experienced emergencies in the sim with all the bells and whistles, then the first time something such as a fire warning sounds for real you are having a new experience, and as such cannot have practiced for it. Having an examiner close a throttle is virtually an expected event, as you can see him move. The sim is much more realistic and a far better training aid.
Recurrent training at FSI or similar is a lot more expensive than an hour in an aircraft. Unfortunately some owners or operators put cost before competance or at least effective training.
I am not making any comment as to the crew involved as I do not know where or how they trained, just making a comment for discussion.
Recurrent training at FSI or similar is a lot more expensive than an hour in an aircraft. Unfortunately some owners or operators put cost before competance or at least effective training.
I am not making any comment as to the crew involved as I do not know where or how they trained, just making a comment for discussion.
Join Date: Mar 2004
Location: schermoney and left front seat
Age: 57
Posts: 2,439
Received 0 Likes
on
0 Posts
Eckhard, I liked your first post. One could just learn from it.
One classical case especially for the small citations is the Power Brake Low Pressure light below 80kts. Some guys I do checkrides with brief that they will stop for any light below 80kts and only for a red one bewteen 81 and V1.
Rejecting for the power brake low pressure light at, say, 79kts can lead to a problem, on a short runway....
I also agree that having an extra criterion at 80kts in a light jet can be unnecessarily complicated, especially on a long runway. On a 'short' runway however, it may help to focus the mind on the 'go case' if one restricts the reasons for a 'STOP' call above a nominated speed (typically 70 or 80kts) to a short list (red lights, etc).
Rejecting for the power brake low pressure light at, say, 79kts can lead to a problem, on a short runway....
Join Date: Mar 2004
Location: schermoney and left front seat
Age: 57
Posts: 2,439
Received 0 Likes
on
0 Posts
Spot on, I like many others did all my initial training in the aircraft, and didnt see a sim for years. When I did it was a real eye opener!
I´ve said it before and say it again, instead of the most things JAR and EASA have introduced to increase safety they should have put the requirement for sim training into their regs and that would have a way higher impact on safety.
I`d gladly turn in my CRI licence...
Join Date: Mar 2002
Location: Euroland
Posts: 2,814
Likes: 0
Received 0 Likes
on
0 Posts
I think that everyone has been talking about two separate issues.
1. The go/stop decision.
With a very very long runway, it may be possible to accelerate to cruise speed and still stop.
However, the V1 speed has to respect the maximum tyre speed so that reduces the maximum speed since it is no good trying to accelerate past a speed where the tyres start to fail.
This speed may also be too high for the brakes (Vmbe) which depends on brake applications during taxi, turn round time etc etc etc. So this may further reduce the V1 speed since it is a bit silly to slam on the brakes at a higher speed than they can stop you from.
Finally, it has been found that it is more efficient to fly the aircraft than to drive it so the manufacturer will have a rotation speed that is set a safe margin above stall and Vmc where it is a good idea to start flying.
Now here is the important bit - one you rotate and start flying you can not abort because it is too late - you are flying - no matter what you do next you have taken to the air and it is too late to change your mind.
Therefore V1 can not ever be more than Vr - ever.
Please read that last statement several times before reading the next.
2. Dealing with an emergency in the ai (even if it is at 10ft and the airborne time is only 1 second).
When airborne and faced with an emergency, the PIC is quite entitled to land the aircraft on that open space in front of them - be that a straight piece of tarmac (that just happens to be the same runway they departed from), a highway or farmer brown's field, it makes no difference. The PIC uses the information available, time available and their knowledge / skill to do the best they can.
So for all those that think landing back on the runway is aborting the take-off, please think again. Once you have left the ground the ability to make a choice of not leaving the ground has passed.
1. The go/stop decision.
With a very very long runway, it may be possible to accelerate to cruise speed and still stop.
However, the V1 speed has to respect the maximum tyre speed so that reduces the maximum speed since it is no good trying to accelerate past a speed where the tyres start to fail.
This speed may also be too high for the brakes (Vmbe) which depends on brake applications during taxi, turn round time etc etc etc. So this may further reduce the V1 speed since it is a bit silly to slam on the brakes at a higher speed than they can stop you from.
Finally, it has been found that it is more efficient to fly the aircraft than to drive it so the manufacturer will have a rotation speed that is set a safe margin above stall and Vmc where it is a good idea to start flying.
Now here is the important bit - one you rotate and start flying you can not abort because it is too late - you are flying - no matter what you do next you have taken to the air and it is too late to change your mind.
Therefore V1 can not ever be more than Vr - ever.
Please read that last statement several times before reading the next.
2. Dealing with an emergency in the ai (even if it is at 10ft and the airborne time is only 1 second).
When airborne and faced with an emergency, the PIC is quite entitled to land the aircraft on that open space in front of them - be that a straight piece of tarmac (that just happens to be the same runway they departed from), a highway or farmer brown's field, it makes no difference. The PIC uses the information available, time available and their knowledge / skill to do the best they can.
So for all those that think landing back on the runway is aborting the take-off, please think again. Once you have left the ground the ability to make a choice of not leaving the ground has passed.
Join Date: Mar 2004
Location: schermoney and left front seat
Age: 57
Posts: 2,439
Received 0 Likes
on
0 Posts
However, the V1 speed has to respect the maximum tyre speed so that reduces the maximum speed since it is no good trying to accelerate past a speed where the tyres start to fail.
This speed may also be too high for the brakes (Vmbe) which depends on brake applications during taxi, turn round time etc etc etc. So this may further reduce the V1 speed since it is a bit silly to slam on the brakes at a higher speed than they can stop you from
This speed may also be too high for the brakes (Vmbe) which depends on brake applications during taxi, turn round time etc etc etc. So this may further reduce the V1 speed since it is a bit silly to slam on the brakes at a higher speed than they can stop you from
DFC, has anyone suggested taking the aeroplane past max tyre?
Lets use the numbers for a CJ...
Highest V1=109 KIAS.
Highest VR=109 KIAS
Highest Vref=113 KIAS (for MLM)
Highest Vref for flaps inop in icing= 138 KIAS
Max Tyre 165 KIAS
I guess taking the airplane 56 knots over V1 was not intended by anyone. Even - if we talk brake energy - going 29 KIAS faster was not what we discussed here I think. BTW, it would require really hard work to keep the airplane on the ground at these speeds.
Brake energy tables in smaller Citations are really simple...meaning: you can stop the airplane from 138 KIAS within ALDR x 1,45 (IIRC) [or higher], to lazy to crawl through th manual, but I think they nowhere mention speed in these tables.
Cessnas are made for simple minds such as me.
Join Date: Mar 2002
Location: Euroland
Posts: 2,814
Likes: 0
Received 0 Likes
on
0 Posts
I think you have missed the point I was making.
Everyone was getting confused with applying V1 and the balanced runway concept on very long runways. Therefore I was pointing out that on a long runway that while in theory a stop could be made from a very high V1, there are other issues preventing V1 from being very high.
As for tyres - don't forget that it is groundspeed that will really be the tyre limit because that is what causes the stress on the tyre. So if you have 225mph tyres then you can not travel down the runway at 225mph and a 10 Kt tailwind and be within limits.
Therefore in a situation where the TAS is a lot higher than the IAS and there is a tailwind, you might not have as much a margin as you think - unless the limit speed has been set a long way beyond the maxc you will ever use.
Everyone was getting confused with applying V1 and the balanced runway concept on very long runways. Therefore I was pointing out that on a long runway that while in theory a stop could be made from a very high V1, there are other issues preventing V1 from being very high.
As for tyres - don't forget that it is groundspeed that will really be the tyre limit because that is what causes the stress on the tyre. So if you have 225mph tyres then you can not travel down the runway at 225mph and a 10 Kt tailwind and be within limits.
Therefore in a situation where the TAS is a lot higher than the IAS and there is a tailwind, you might not have as much a margin as you think - unless the limit speed has been set a long way beyond the maxc you will ever use.
