Limiting Factors For Takeoff

[AeroTech]

Hi,

By order of importance what are the limiting factors for takeoff on majority of runways. Through some posts the climb gradient for second segment is the number one, but one of the guru in this forum said it's not necessearily true.

Feedback appreciated.
Regards

[PappyJ]

The ability to stop is a fairly important limiting factor!

[de facto]

Hi there,

Many factors are taken into account for Takeoff performance and most pilots are aware of it.(low Qnh,runway contamination,aircraft limitations...)
However on B737s, emergency turns at V2 banking into the failed engine may be fatal if unaware of spoiler turn assist problems.
Not banking into the good engine may drastically reduce the Vmca on which V2 minimum is calculated from.
So if you have the choice,turn into the good engine as it is how Vmca was calculated in the first place.(3-5 degrees).

Most crews are unaware of Missed approach climb gradient performance limitation for their aircraft,which should be known before dispatching the flight...


1)Runway(lengh/width) limit
2)0bstacle limit
3)Climb limit
4)Aircraft/weather/Crew limit

[johns7022]

The question is moot...any factor that limits your ability to get off the ground is not more or less important, it's simply a go/no go decision...

You might be smart and simply start at the most restrictive factor that day, then move backwards...but ALL limiting factors have to be calculated, addressed, solved, so they aren't limiting any more....

[Air Tourer]

Pardon?

Not sure what AeroTech means on this one. What does second segment mean? On most runways I'd of guessed Max T.O. weight was the basic limit.

[hetfield]

Air Tourer

Have a look

[mutt]

Aero Tech, there is no single answer, it depends on the aircraft and airport. For example:

B747-300 Surabaya is field length limited, the B747-400 is 2nd segment climb limited.

B747-300 Madinah is Obstacle Limited, the B747-400 is 2nd segment climb limited.

And if you really want an interesting one, look at a MD11 from a hot/high airport and you will find that it is limited by its ability to dump fuel

Mutt

[FE Hoppy]

Your max take off weight is going to be limited by any one of:

Structural Limit
Field length All engines
Field Length One engine inop
Climb 1st segment
Climb 2nd segment
Climb 3rd segment
Climb final segment
Climb missed approach
Tyre speed
Vmbe
Vmc
Obstacle clearence
Something else I've probably forgotten

They all have equal importance as which ever is most limiting is limiting!

Which is most common depends on aircraft type and runway and no two are the same. So there is no answer to your question in it's current form.

[john_tullamarine]

Not banking into the good engine may drastically reduce the Vmca on which V2 minimum is calculated

increase, perhaps ?

Air Tourer
Have a look

Hetfield, I suggest that you bin whatever book you got that dreadful sketch from ... riddled with confusion.

TOD - to 35ft
first - to end of gear retraction
second - to beginning of level acceleration
third - acceleration and flap retraction
fourth - final climb (for most types)
fifth - final climb (for some types)

FE Hoppy

add ASD, TOR, LW plus burn and, if you list Vmc, then Vmcg as well, perhaps .. likewise, I've probably missed a few as well

[Pugachev Cobra]

May I suggest a better graphic?

Interesting to know that some aircraft have a 5th segment. What would be the difference then?

[hetfield]

@JT

Yep, sorry it's a simplification on the fast run

[Piltdown Man]

For the most recent types I have flown, the most common restriction has been MTOW. In second place, say 20% it is MLW and third place at say 5%, is performance (with the exception of LCY ops, when virtually every takeoff was performance limited). However, for my current type (E190), performance has never been a restriction. To date it has just been a case of turning the wick up to lift the given payload.

PM

[rudderrudderrat]

Hi AeroTech,

the limiting factors for takeoff on majority of runways

for us it's the 2nd & 3rd segments. If they are really restrictive then we use an Non Standard Engine Out (Emergency Turn) Procedure to avoid the major problem, and / or raise the Minimum Acceleration Altitude.

We hardly ever have to use full T.O.thrust (normally use flex power reduction) so it's not very often a TODA / ASDA restriction.

[john_tullamarine]

Interesting to know that some aircraft have a 5th segment. What would be the difference then?

Only seen the one I can recall at the moment (AW650 Argosy - Britain's Queen of the Skies) .. allowed for a final acceleration to enroute climb.

Pugachev Cobra

Much better diagram .. however, one trusts that the originator intends the aircraft to be several seconds off the ground before selecting wheels up ?

The original question is interesting but has no definitive answer .. very much a case of "it depends" ...

[captjns]

Can't forgest about landing weight next station and enroute climb limit weights when routing takes you over mountainous terrain?

Some older jets are effected by pressure altitude and temperature limits too.

[Intruder]

The original question is interesting but has no definitive answer .. very much a case of "it depends" ...

It is much less interesting considering the fact that the OP posted 2 similar questions then disappeared.

When someone posts a question like that, then does not participate in the ensuing discussion, I consider the person a troll and not worthy of future responses. i can understand a newbie or 3 coming on with a question AND a lack of knowledge of the SEARCH function, but those are relatively rare. This particular OP has supposedly been here for 5 years, so he knows better...

[john_tullamarine]

Then again, it probably doesn't matter all that much .. if the question, regardless of the motives of the poster, is interesting, it will attract responses .. if not, it will die a quick death and sink into the fetid archival abyss.

[Air Tourer]

Thanks

Thanks fellas, I expected a flogging, but I learn't something even from the first sketch. And I certainly didn't know about a leveling off in a 3rd segment. As for searching, I can never get the right words. As for the O.P. he got plenty to think about. John L.

[john_tullamarine]

leveling off in a 3rd segment

applicable to heavy aircraft .. with a caveat that, for many of the overpowered twins around, the application is a shallow climb to match acceleration to flap retraction times.

For lighties the takeoff is much simpler - distance to screen and a climb gradient requirement for initial climb and then you're on your own ...

[legacy]

In order of importance..

(You'll first need a runway that is sufficient
Take off Distance Available (TODA)
Take off Run Available (TORA)
wet runway limitations for accelerated stop distance
runway slope/gradient

.... and also as mentioned:

Structural Limit
Field length All engines
Field Length One engine inop
Climb 1st segment
Climb 2nd segment
Climb 3rd segment
Climb final segment
Climb missed approach
Tyre speed
Vmbe
Vmc
Obstacle clearence