Take-off performance
Navigation · Chapter 53 · DGCA CPL and ATPL
Build the runway, then call each take-off before you watch it run.
Remember
- Stopway: ASDA. Clearway: TODA, max half TORA.
- Displaced threshold: LDA only.
- Heat, height, mass, tailwind, upslope: longer.
- Crosswind = wind × sin angle.
- More flap: shorter run, worse climb.
What the runway offers
A runway publishes four numbers: what it offers. Your aeroplane has four matching ones: what it needs.
Take-off is allowed only if every need fits inside its offer.
TORA, take-off run available: the length you can roll on.
You must be airborne before it ends.
Add a stopway beyond the end: a strip strong enough to stop on, but not for normal use. Now you have an ASDA, accelerate-stop distance available.
ASDA = TORA + stopway
Add a clearway beyond that: open ground with nothing in the way. Not for rolling, but you may fly over it climbing to 35 ft. That is TODA.
TODA = TORA + clearway
Displaced threshold: an obstacle before the runway means you may not land on the first part, but you may still roll on it for take-off. Only LDA shrinks.
Stopway: ASDA only. Clearway: TODA only. Displaced threshold: LDA only.
LDA = runway − displaced threshold
Stopway and clearway
The exam asks more about these two strips than anything else on the page.
A clearway has an imaginary centre line: not marked on the ground, but shown on charts. It is within the airport boundary, and may include the stopway.
What each buys you. Stopway lets you decide later: a higher V1. Clearway lets you lift more mass, at a lower V1.
What the aeroplane needs
This lesson is part of the Navigation plan. See plans
Call it
This lesson is part of the Navigation plan. See plans
Wind on the runway
This lesson is part of the Navigation plan. See plans
Flap, sums, thrust
This lesson is part of the Navigation plan. See plans