Reverse thrust & landing distance?

[DJ Flyboy]

Is two engine reverse thrust or only one engine reverse thrust taken into consideration while calculating landing distances and is it idle or full?

[FlyingStone]

No reverse on dry runways, full reverse (as operative) for wet & contaminated.

[DJ Flyboy]

Thanks, but do we consider 2 eng rev thrust or just one?

[JeroenC]

In the engine failure case just 1;).

[Denti]

Guess it depends. For dispatch calculation the reversers are not taken into consideration if the weather forecast suggests a dry runway.

Inflight you can take reverse thrust into consideration, at least it is the standard selection on our airbus iPad software, in that case it calculates based on full reverse thrust. It is easy enough to deselect it though, which is a good idea, especially if planning on using idle reverse.

[safetypee]

Reverse thrust is not normally considered in certificated performance.

Manufacturers ‘actual’ distances should specify the level of reverse assumed e.g. Boeing rev detent. There should be a separate landing distance table for pre-planned single eng reverse.

If you use 2 eng reverse, then it is the captain’s responsibility to consider a failure during landing; either eng failure or reverse not deploying. Although these failures might appear remote, the reason for certificated performance not considering reverse could be that the sufficient level system reliability was not proven.

Thus if a limited distance landing is based on 2 eng reverse, then the risk of rev failure has to be judged and possibly justified by the crew.
Also, consider what the manufactures’ landing distances assume; a long or fast landing without rev failure might not assure stopping within the published distance.