Landing Distances

[fairb]

Studying for the Flight Planning exam and trying to work out the definitive source for landing distances. Pooley's, PPL Perfector and AIC 127/2006 don't seem to agree on the scaling factors that apply to grass take-offs. Tend to think I should go with what the AIC states. Any ideas?

[ChickenHouse]

The ultimate source for estimation of landing distances is the serial number matched POH of the aircraft in question.

There are some rule of thumbs around, but they are just that - bare minimum estimates with no legal or reality binding claims I know off. Each aircraft will be different and the POH will give an idea how, but not be the last answer. Especially grass take offs are often pilot guts feeling skills, as grass usually does not follow aviation standardization rules, it is a natural growing commodity with no sense for regulations. Let it be 75% humidity at take off and it will behave different to the time you landed at 65% ...

[tmmorris]

The CAA safety sense leaflet (http://publicapps.caa.co.uk/docs/33/20130121SSL07.pdf) is conservative but does offer a good margin of safety to allow for the sorts of variables Chickenhouse mentions. But you MUST start from the POH figures and that means working through the charts/graphs/tables for that specific aircraft.

[alex90]

I would always run the numbers to see if it is possible, and then apply safety margins and finally have my own input on how I think the plane will behave.

The safety sense leaflet shows how the calculations ought to be done: safet sense leaflet pdf (http://publicapps.caa.co.uk/docs/33/20130121SSL07.pdf) and there is a link to AIC 127/2006 AIC (http://www.ead.eurocontrol.int/eadbasic/pamslight-E20423FA4B7CF4086D6653E8BC0B279F/7FE5QZZF3FXUS/EN/AIC/P/127-2006/EG_Circ_2006_P_127_en_2006-12-07.pdf) for exact figures to be used.

From memory this was the required factors for the exam, but something to note in real world flying is when the aeroplane's POH was published and/or amended to check whether or not they already included the CAA 30% safety margin factor.

I hope this helps!
Alex

[alex90]

Haha tmmorris beat me to it!!