V1 question.
Join Date: Aug 2007
Location: coeland
Posts: 32
Likes: 0
Received 0 Likes
on
0 Posts
too fast n too much inertia n too little tarmac left at V1.
You are in the high speed regime, above 100knots .if u read annex 6 and FAR25, you will get all the answers.read up on " Balanced Field Length".
I ever had a RTO at 87knots and it was anything but gentle.
In performance, we are not actually learning what the aircraft can do but rather what it CANNOT do. that's called Limitations and that's why we have to calculate Field Length limit, climb limit, obstacle clb limit..fwd CG, tailwind limits, bla..bla..bla..
Nothing is perfect, machines or humans. safety is numero uno!
What they guys say here are correct but shouldn't u have learnt and passed this subject in Perf A before flt? Don't get me wrong , im just curious.
Cheers n happy flight!
"Thanks guys, that makes sense.
As a point of interest, why is a T/O never rejected after rotate but before lift-off?"
You are in the high speed regime, above 100knots .if u read annex 6 and FAR25, you will get all the answers.read up on " Balanced Field Length".
I ever had a RTO at 87knots and it was anything but gentle.
In performance, we are not actually learning what the aircraft can do but rather what it CANNOT do. that's called Limitations and that's why we have to calculate Field Length limit, climb limit, obstacle clb limit..fwd CG, tailwind limits, bla..bla..bla..
Nothing is perfect, machines or humans. safety is numero uno!
What they guys say here are correct but shouldn't u have learnt and passed this subject in Perf A before flt? Don't get me wrong , im just curious.
Cheers n happy flight!
"Thanks guys, that makes sense.
As a point of interest, why is a T/O never rejected after rotate but before lift-off?"
Moderator
to do that it usually does not use the lowest V2/Vr combination but rather slightly higher to much higher speeds
V2 overspeed (improved performance in AB lingo) takeoffs will improve weight compared to min V2 schedules until whatever limitation occurs to preclude further V2 increase.
Difference between Vr and V2 is usually only 2 to 3 kts
Which is why we don't normally concern ourselves with the V2/VR ratio - rather V1/VR
not enough even for the OEI case to just reach V2 at screen height
Can't speak to the NG but, for the Classic, rotating at VR, OEI, will approximate V2 at screen. AEO, of course, screen speed will be substantially greater than V2.
So in all practical application V2 and Vr are not fixed values
Absolutely correct save for the following caveat. VR is constrained by V2. At very low weights, V2 WILL be constant with changing weight (Vmc limited) until the weight increases to the point where V2 becomes stall limited. Overspeed schedules are used to exploit the improved climb performance at speeds modestly in excess of V2 min.
V2 overspeed (improved performance in AB lingo) takeoffs will improve weight compared to min V2 schedules until whatever limitation occurs to preclude further V2 increase.
Difference between Vr and V2 is usually only 2 to 3 kts
Which is why we don't normally concern ourselves with the V2/VR ratio - rather V1/VR
not enough even for the OEI case to just reach V2 at screen height
Can't speak to the NG but, for the Classic, rotating at VR, OEI, will approximate V2 at screen. AEO, of course, screen speed will be substantially greater than V2.
So in all practical application V2 and Vr are not fixed values
Absolutely correct save for the following caveat. VR is constrained by V2. At very low weights, V2 WILL be constant with changing weight (Vmc limited) until the weight increases to the point where V2 becomes stall limited. Overspeed schedules are used to exploit the improved climb performance at speeds modestly in excess of V2 min.
Join Date: Feb 1998
Location: Formerly of Nam
Posts: 1,595
Likes: 0
Received 0 Likes
on
0 Posts
regarding the rejecting take off after VR... Never an option
on the remaining runway very safely after he'd copped a fire
warning just after lift off.
There was a lot of truths, half-truths and total bull**** on the
relevant threads at that time. I for one learned a lot from the
timely actions of that bloke.
Moderator
landed on the remaining runway very safely after he'd copped a fire
warning just after lift off.
Given enough runway, of course that is an option.
However,
(a) the captain presumably had some explaining to do - I vaguely recall the incident but not the investigation.
(b) had the outcome been a mishap, the consequence might have been far more difficult for the captain.
While acknowledging that SOPs don't cover all situations and captain's prerogative, routine risk management generally dictates SOP compliance as being the reasonable way to go.
warning just after lift off.
Given enough runway, of course that is an option.
However,
(a) the captain presumably had some explaining to do - I vaguely recall the incident but not the investigation.
(b) had the outcome been a mishap, the consequence might have been far more difficult for the captain.
While acknowledging that SOPs don't cover all situations and captain's prerogative, routine risk management generally dictates SOP compliance as being the reasonable way to go.
Thread Starter
Join Date: Oct 1999
Location: UK
Posts: 3,325
Likes: 0
Received 0 Likes
on
0 Posts
IIRC that 748 had a fire in the engine or wing at or very soon after lift off. The captain judged that the fire was so severe that the structure would not stay intact for even a tight circuit, so he chopped the power and landed ahead. I think they all walked away.
Join Date: Sep 2002
Location: La Belle Province
Posts: 2,179
Likes: 0
Received 0 Likes
on
0 Posts
Report No: 3/2001. Report on the accident to HS748 Series 2B, G-OJEM, at Stansted Airport on 30 March 1998 - HS748 Series 2B, G-OJEM is presumably the incident being referred to. (?)
JT,
I think I gave good reasons for the term 'fudge' but, as I said, it's the best we have.
Recollect once querying why one twin jet we flew had a lower Vmcg (or was it Vmca? - forgotten now) on the version with the more powerful engines. Came the answer: "It's what's demonstrated by the test pilot on the day."
I think I gave good reasons for the term 'fudge' but, as I said, it's the best we have.
Recollect once querying why one twin jet we flew had a lower Vmcg (or was it Vmca? - forgotten now) on the version with the more powerful engines. Came the answer: "It's what's demonstrated by the test pilot on the day."
Join Date: Jun 2002
Location: Wor Yerm
Age: 68
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
I am very happy that everybody escaped with their lives after this crash (this wasn't an accident). But...
And let me be very clear - that is called luck! To assess that the wing would have burnt off (because of a bang, a few screams in the cabin and possibility that the No. 1 told you that there was an engine fire) and that from 60-100 ft above the runway at 11:30pm that there would be enough room to land is something only worthy of a someone who believes in Intelligent Design and Creationism.
I have also learnt a great deal from that bloke as well.
PM
...and landed on the remaining runway very safely...
I have also learnt a great deal from that bloke as well.
PM
Join Date: Sep 2002
Location: La Belle Province
Posts: 2,179
Likes: 0
Received 0 Likes
on
0 Posts
From the report, it was hardly "very safely" - they overran the remaining runway at 62kts according to AAIB, which is non-trivial overrun speed. Depending on who you ask, 70-80 knots represents the speed at which an overrun should be considered potentially Catastrophic, which is the most severe category for a safety assessment.
Though the AAIB don't, in fact, challenge the pilot's decision.
Though the AAIB don't, in fact, challenge the pilot's decision.
Join Date: Jul 2011
Location: Somewhere
Age: 42
Posts: 55
Likes: 0
Received 0 Likes
on
0 Posts
Wow..surprised the PPRUNE server isn't melting down at the acknowledgement that all planes don't magically fly after V1.
I ponder how many people JT has banned who simply made the comment that a captain with 5000 feet of runway post V1, can stop his aircraft safely...
Hell's freezing over....
I ponder how many people JT has banned who simply made the comment that a captain with 5000 feet of runway post V1, can stop his aircraft safely...
Hell's freezing over....
Moderator
"It's what's demonstrated by the test pilot on the day."
That MAY be true but are you sure that the engine upgrade didn't involve anciliary mods which might have had some relevance to Vmc considerations ?
The captain judged that the fire was so severe that the structure would not stay intact for even a tight circuit
Command prerogative is there for such decisions. However, no-one in the circumstances could make a rational call on that so the decision can only be seen to be a knee-jerk reaction to the situation. All of us who have had time on Darts would have a heightened concern about uncontained engine fires so the captain's decision is not entirely strange.
Overall, continuing for a circuit has the better outcome numbers on risk history. Having said that, if I were faced with similar circumstances and, say, 10-14,000 ft of runway, I'd be doing the same thing. However, the report suggest he landed with not very much seal in front of him and proceeded to depart the runway head at VERY significant speed for a Draggie. Probably not a good call to try and justify to the Chief Pilot over tea and bikkies - actually, probably without the tea and bikkies ?
it was hardly "very safely"
That's an understatement. Thanks for the link - I had read this report long ago and had the same thoughts then.
all planes don't magically fly after V1
Of course they don't.
Certification Standards and SOPs address reasonably expected circumstances. If the situation is dreadfully out of left field, then all bets are off and the captain earns his year's salary in the next few seconds or minutes ....
The very great majority of situations, however, will have a better likelihood of a satisfactory outcome by following sensible SOPs. No guarantees at all .. but the historical numbers are on the side of SOPs.
I ponder how many people JT has banned who simply made the comment that a captain with 5000 feet of runway post V1, can stop his aircraft safely
Actually, I have no idea how many folk I have chastised - probably not more than I could count on the fingers of one hand and certainly none for the sort of reason that you cite.
Caveat - a couple of troublesome folk who have gone through an interminable succession of re-incarnations have had recurrent slaps on the wrist applied. On that point, should I hold some interest as to why your comment is vaguely familiar in its style ?
That MAY be true but are you sure that the engine upgrade didn't involve anciliary mods which might have had some relevance to Vmc considerations ?
The captain judged that the fire was so severe that the structure would not stay intact for even a tight circuit
Command prerogative is there for such decisions. However, no-one in the circumstances could make a rational call on that so the decision can only be seen to be a knee-jerk reaction to the situation. All of us who have had time on Darts would have a heightened concern about uncontained engine fires so the captain's decision is not entirely strange.
Overall, continuing for a circuit has the better outcome numbers on risk history. Having said that, if I were faced with similar circumstances and, say, 10-14,000 ft of runway, I'd be doing the same thing. However, the report suggest he landed with not very much seal in front of him and proceeded to depart the runway head at VERY significant speed for a Draggie. Probably not a good call to try and justify to the Chief Pilot over tea and bikkies - actually, probably without the tea and bikkies ?
it was hardly "very safely"
That's an understatement. Thanks for the link - I had read this report long ago and had the same thoughts then.
all planes don't magically fly after V1
Of course they don't.
Certification Standards and SOPs address reasonably expected circumstances. If the situation is dreadfully out of left field, then all bets are off and the captain earns his year's salary in the next few seconds or minutes ....
The very great majority of situations, however, will have a better likelihood of a satisfactory outcome by following sensible SOPs. No guarantees at all .. but the historical numbers are on the side of SOPs.
I ponder how many people JT has banned who simply made the comment that a captain with 5000 feet of runway post V1, can stop his aircraft safely
Actually, I have no idea how many folk I have chastised - probably not more than I could count on the fingers of one hand and certainly none for the sort of reason that you cite.
Caveat - a couple of troublesome folk who have gone through an interminable succession of re-incarnations have had recurrent slaps on the wrist applied. On that point, should I hold some interest as to why your comment is vaguely familiar in its style ?
Those who wish to form their own conclusions and/or learn from the HS 748 accident should readthe full report.
The aircraft suffered an uncontained engine failure and subsequent fire; it was at night and there was a bright glow visible in the cabin.
The AAIB report handles the HF aspects very sensibly, with consideration of the likely surprise (shock) of the situation (my supposition), which probably contributed to the decision to land, as it may have done in the failure to follow all of the shutdown procedures – failure to close the LP fuel cock.
Errors stem from the influence of factors in the situation. At times, these factors exceed the human capabilities of analysis and rational decision making, which with the pressure of time and personal threat can result in non standard actions.
These issues are often found in accidents when attempting to stop after V1.
The aircraft suffered an uncontained engine failure and subsequent fire; it was at night and there was a bright glow visible in the cabin.
The AAIB report handles the HF aspects very sensibly, with consideration of the likely surprise (shock) of the situation (my supposition), which probably contributed to the decision to land, as it may have done in the failure to follow all of the shutdown procedures – failure to close the LP fuel cock.
Errors stem from the influence of factors in the situation. At times, these factors exceed the human capabilities of analysis and rational decision making, which with the pressure of time and personal threat can result in non standard actions.
These issues are often found in accidents when attempting to stop after V1.
Join Date: Jul 2011
Location: Somewhere
Age: 42
Posts: 55
Likes: 0
Received 0 Likes
on
0 Posts
Gee whiz....you haven't rotated yet, you see a mile of runway left...is it really that hard to consider keeping the burning wreck on the ground rather then fly it up in the air?
At issue here isn't logic, but the fact that the airlines, and military have culled so hard for followers rather then thinkers that any concept no matter how logical, that hasn't been handed down from the chief pilot, must be dangerous.
Like lemmings off a cliff, I ponder how many pilots have pulled a broken aircraft into the air, only to fly it to the scene of the accident.
At issue here isn't logic, but the fact that the airlines, and military have culled so hard for followers rather then thinkers that any concept no matter how logical, that hasn't been handed down from the chief pilot, must be dangerous.
Like lemmings off a cliff, I ponder how many pilots have pulled a broken aircraft into the air, only to fly it to the scene of the accident.
Whenrealityhurts
If "broken" airplanes were taken airborne and crashed, when they could have stopped, I don't think the SOPs surrounding V1 would be THE industry standard. The record is quite clear--the statistics say taking it airborne is safer. Yes, statistics and safety is about probabilities, not absolutes. On almost 15,000 feet of runway at JFK, a TWA L-1011 aborted AIRBORNE after a false stall warning, everyone got out of the fire following a very hard landing and severe damage. Was that the right decision?
GF
PS: At least in the USAF I graduated from, pilots were anything but followers. My acquaintances in the RAF, RAAF and RCAF would be shocked at such an accusation. An AF doesn't have any combat capability with a flight crew force of followers. I include the enlisted members in that assertion.
If "broken" airplanes were taken airborne and crashed, when they could have stopped, I don't think the SOPs surrounding V1 would be THE industry standard. The record is quite clear--the statistics say taking it airborne is safer. Yes, statistics and safety is about probabilities, not absolutes. On almost 15,000 feet of runway at JFK, a TWA L-1011 aborted AIRBORNE after a false stall warning, everyone got out of the fire following a very hard landing and severe damage. Was that the right decision?
GF
PS: At least in the USAF I graduated from, pilots were anything but followers. My acquaintances in the RAF, RAAF and RCAF would be shocked at such an accusation. An AF doesn't have any combat capability with a flight crew force of followers. I include the enlisted members in that assertion.
Join Date: Sep 2002
Location: La Belle Province
Posts: 2,179
Likes: 0
Received 0 Likes
on
0 Posts
For those who haven't looked at the report, the very first page of the "Appendicies" pdf contains a diagram of the runway, with points of interest marked. Also shown is the distance from the start of RWY 23, which was approx 3000m long. The following are estimated, but good to at least 100m, maybe 50m.
So the actual event happened with 1750m of "runway left". Deciding to get back down, and then doing so, took more than 3/4 of that distance. Leaving just over 1000ft in which to stop. Which should give pause for thought for anyone thinking of putting a damaged plane back down again. Especially if they start any further down the runway than this event...
- rotation : 1150m
- Bang : 1250m
- Engine debris : 1300m to 1800m
- HP Disc fragments : 1550m
- Touchdown : 2600m
- Aircraft Stop Point : 3200m
So the actual event happened with 1750m of "runway left". Deciding to get back down, and then doing so, took more than 3/4 of that distance. Leaving just over 1000ft in which to stop. Which should give pause for thought for anyone thinking of putting a damaged plane back down again. Especially if they start any further down the runway than this event...
Moderator
At issue here isn't logic ..
On the contrary I suggest that that is the pivotal issue.
Like lemmings off a cliff, I ponder how many pilots have pulled a broken aircraft into the air, only to fly it to the scene of the accident
Somewhat fewer, I suggest, than those who have rejected post-V1 and come to grief. There are no guarantees, only probabilities. Sensible folk stake their lives and superannuation on the numbers game. Only in the rarest of situations is the spur of the moment call going to win the day. Of course it happens - sometimes - but the odd successful exception doesn't invalidate the general rule.
I think that GF and MFS have summarised the situation succinctly ?
On the contrary I suggest that that is the pivotal issue.
Like lemmings off a cliff, I ponder how many pilots have pulled a broken aircraft into the air, only to fly it to the scene of the accident
Somewhat fewer, I suggest, than those who have rejected post-V1 and come to grief. There are no guarantees, only probabilities. Sensible folk stake their lives and superannuation on the numbers game. Only in the rarest of situations is the spur of the moment call going to win the day. Of course it happens - sometimes - but the odd successful exception doesn't invalidate the general rule.
I think that GF and MFS have summarised the situation succinctly ?
Join Date: Aug 2003
Location: Sale, Australia
Age: 80
Posts: 3,832
Likes: 0
Received 0 Likes
on
0 Posts
GF, you may not have picked up on the new persona we are blessed with - our old friend. On the other hand I may be telling you how to suck eggs. 
JT, to his credit, has him sussed.
Love it.
JT, to his credit, has him sussed.
Caveat - a couple of troublesome folk who have gone through an interminable succession of re-incarnations have had recurrent slaps on the wrist applied. On that point, should I hold some interest as to why your comment is vaguely familiar in its style ?
Join Date: Feb 1998
Location: Formerly of Nam
Posts: 1,595
Likes: 0
Received 0 Likes
on
0 Posts
Report No: 3/2001. Report on the accident to HS748 Series 2B, G-OJEM, at Stansted Airport on 30 March 1998 - HS748 Series 2B, G-OJEM is presumably the incident being referred to. (?)
would have it.
Particularly interesting on the report is..... 3. Conclusions -
(a) Findings - paragraphs 4 and 5 (p83/87).
I don't think anyone is familiar with just how bloody dangerous a
wing mounted Dart fire can be. That bloke certainly did, and faced
the enquiry very much alive, as did his crew and entire pax.
Anyway it was all said here before, 13 odd years ago.
JT,
Don't know. Did cross my mind that the rudder was larger but never checked.
That MAY be true but are you sure that the engine upgrade didn't involve anciliary mods which might have had some relevance to Vmc considerations ?