I can fully understand the reluctance to incorporate a calculator due to the given reasons. This is the one thing I always do by hand with the use of the POH when flying to an airfield where this could be critical (short runway, hot & high, etc.). The problem I have is where to put this manually calculated number. It would be great if SD would at least have a text field where we could manually enter the calculated TO / LDG distance so it is logged / printed in our pilot log.

I think we’d all agree that one should use POH data wherever possible. One of the practical difficulties involved in trying to create a universal performance calculator is the variability of detail and presentation of such data across different aircraft types. Some POH use graphs, some use tables. Some include factors such as runway surface, some don’t. Where such factors are missing in the POH data, it’s then a matter of judgement what to use. 

Another request for this, it's the only thing missing from the app. Start with the two most common aircraft or have lots of empty boxes where the user inputs data and the formulas behind the scenes do the work ... 

People have enough trouble setting up their aircraft's (relatively simple) weight and balance data. Setting up a feature like takeoff and landing distance calculations would be an order of magnitude harder, at least. I never say never, but I really can't imagine us doing this in SkyDemon.

Because if the wide variability of conditions not easily included in such a calculation, whatever number you do get out will be worth next to nothing. This questionable benefit is countered by the added complexity of entering your aircraft's data into SD as well as the danger of pilots relying on this and then not making it.

There just are some things which are better left to the pilot's judgement.

-- Chris.

I wonder if we are confusing calculations and estimating.

For most light aircraft on grass IMHO it's always seemed more a case of good judgement and experience, it's not really a calculation at all - and it's usually short grass strips where the distance available is going to be most marginal. 

Many of the significant factors involved in estimating are very subjective - e.g. how damp or soft the ground is, or how long the grass is. A few weeks back the only option was to taxi along the runway to judge how soft it was and judge the impact .... (if you need 1700rpm to taxi you know it's going to be tight!) - there's no way to 'calculate' the softness of the runway.  

So whilst there could be a nice like calculator in SkyDemon with standard take-off factors etc - I do wonder if this is an area where as GA pilots we've been trained in an erroneous pursuit of spurious precision. The real point of the going through the take-off factors is not the number that pops out the end - but rather a checklist of factors to consider - if SkyDemon calculated the answer for you, you'd no longer be going through the checklist.

Just a new plea for this functionality - landing and TO distance calculator...

One of the common causes of incident and accidents remains the misjudging of take-off and landing runs on grass runways - so there is real potential here....

Agreed 1: There is a lot of variables, but some of the central ones are already at hand  - such as weight, elevation+temperature (Density altitude), runway slope, runway surface (not condition) - so a few POH curves on distances are required to be added to the aircraft profile in order to use this feature

Agreed 2: There is many ways to calculate the influence of the various factors - but "Safetysense Leaflet 7c Aeroplane Performance" would be a sensible solution - will not cover all and everything - but would be better than nothing... including relevant safety factors and disclaimers....

What do you think?



CAVOK and Happy landings to all,
/Henrik (HEJ)

Hello,
from my point of view it would be really very helpful to have such a tool. The takeoff and landing calculations have to be done by a pilot anyway. And so, he/she needs to know how to do it and it is not a argument to say, that it is to complicated. The tool does not have to do everything automatically. For me it would be enough to have a sheet for each runway (start, landing, alternate) that contains all the known data. toda, tora, exp. temperature, runway surface. .... And then some free input fields, where the pilot can enter the base runway from operating handbbook and some additional offsets. And then skydeamon calculates evrything together and prepares a sheet, that can be printed out.

Today I do it exactly the same way in excel. But this is some effort, to collect the data.

So I would really support this request.

A take-off and landing distance calculator would be too comoplicated, in my opinion, to setup and use correctly. Just note how many people have problems setting up weight & balance data. Also, these distances depend on a lot of variables: temperature, dewpoint, atmospheric pressure, altitude, weight, surface conditions, wind and pilot skills. I believe it would even be dangerous if people delegate these considerations to a piece of software and possibly faulty input.

Without wanting to tread on anybody's toes, I am the kind of guy who questions why people even bother to get into a plane if they have the software do all the prep work, the GPS do all the nav work, and the AP do all the flying.

-- Chris.

Mhh... shouldn't be too complicated, because other PC based planning software provides this feature. See http://www.flightplanner.de/. Sorry - this site is in German and so is the screenshot - I could not find an English Version.