I’m always looking for new places to fly, but something has been bugging me for a long time and I thought I’d get some input in both the sim world and IRL as well. I’ve looked online and noticed that there are many varying lengths when it comes to how long of a runway a plane needs to land. I understand that there are mitigating factors involved such as sea level, temperature, and that kind of thing, but here’s my question.
Let’s say that you’re in the sim and you have a jet, and you’ve found the published required takeoff distance is 4,800 feet. If you’re looking for a place to land and you see that it has a runway that is 4,750 feet long - do you even consider it? Do you only land where there are longer runways than is required? Does it depend on environmental factors for that day? Do you land hoping the reversers will slow you down? I get that this is a sim and no one is going to get hurt, but I’m curious as to how you approach (no pun intended) that issue.
And how does this work IRL? If the plane “needs” 4,800 feet and the runway lists as 4,790 feet, is it “alright” to land there if the factors are in favor, or do pilots automatically bypass it?
Just a minor comment here. Take of distance and landing distance for a given plane are (almost?) always different. Both typically have their own calculators based on elevation, temp, winds, payload, etc… and they are never the same for takeoff and landing.
I don’t know how much it helps but I remember hearing from a real life King Air pilot that when you fly commercial operations I.e taking paying passengers you DO NOT EVER TAKE ANY RISKS. He mentioned about always allowing slightly more distance than you officially need.
On that note reversers will do nothing on a dry runway but they will help reduce the (longer than normal distance) on a contaminated runway.
I guess if the weather changes for the worse at destination before you’ve got there or before you’ve departed again then you’re going to need to factor in these possibilities happening otherwise you’re going to be stuck.
I.e always aim for the worse case scenario and then factor in slightly more.
In real life most pilots that want to remain alive use the 50% rule, always add 50% to calculations such as minimum runway length for takeoff and landing. the reason being these are the numbers calculated by engineers for a brand new aircraft when it was built. ALL kinds of things come into play. Condition of runway (wet, beat up, some sand etc). Aging plane, dirt, etc, condition of engines etc. If my POH tells me I need 4800 feet to land at a very specific altitude density, air temperature, wind condition etc, I will not land on a runway less than 7200 feet.
To quickly answer your specific question of requires 4800 feet to land and runway is 4790, not only is it not ok, its illegal, and if something happens, insurance company says see ya, good luck with that.
There are many variables involved in making a safe decision. For airliners the manufacturers test pilots perform landings and take offs and then an an additional allowance is made for real world operations. Currently for take offs an addition 67% is added to the distances and then these figures are published for sea level at standard conditions, calm winds, 15 degrees centigrade and a pressure of 1013 HP/29.92 inches. Any runway operations at different altitudes or weather conditions will affect the performance and distances required.
I did create a runway performance calculator for a number of airliners, which is available as a free download from Flightsim. To.
Search for the Aircraft Runway Performance Spreadsheet.
I am currently working on an improved version with addition aircraft, but the current one will hopefully give you a better understanding of the complexities involved in defining a safe distance for take off or landing.
Very small variables can add a LOT of distance to takeoff and landing. Consider a few knots of tailwind (or a few knots less headwind), runway slope, density altitude, or weight can significantly change the calculations that are generally already based on perfect technique and specific conditions. There is often a ton of interpolation required as well, so it gets a bit loose, anyway.
Thus, I wouldn’t ever consider the published distances as hard and fast, rather a best-case scenario that requires a lot of fudge-factor to be safe.
If your an insurance company, NTSB, FAA, there is no threshold. A more practical example I know my max takeoff weight in my cessna is 1670 lbs. Now, I am sure I have been slightly overweight maybe by 5 or 10 lbs once or twice because of how low that weight actually is, don’t knwo actually weight of flight bag sometimes , passengers are not 100% sure of their own weight etc etc. However 1670 is legal, 1671 is not. Lets say I accidentally miscalculated and my takeoff weight was 1675, and I had an accident, if the NTSB is able to determine that my takeoff weight was 1675 even though it may not have had anything to do with the accident, insurance and FAA immediate flag that I was flying illegally. So i do my best to make sure I am as far underwright of that 1670 as possible when flying.
Fire it up and go and hope it more or less fits on landing
Within reason, 330-900 into Gibraltar yesterday, that’s maybe cutting it a bit tight? Certainly is for parking. Wouldn’t try the 330 into St Bart’s as that’s just daft, basically if it seems reasonable will give it a go and not get hung up too much on the actual numbers.
To be fair, I have been requested by ATC on vatsim if a runway will be enough for me to land on. After double checking the numbers, I had calculated less than 1000 feet remaining
I told ATC it would be fine, but they should have EMS on standby in case of overrun
It’s a simulator….the FAA is not going to come barging through the door. I have landed a very light L-749 in Lukla in the old FS just to prove that it can be done without damage. It even managed to take off….but not fly to the nearest airport.
Landing and Takeoff are completely different things as far as the required runway length goes. But both are affected by a great many factors and even small differences can make a huge difference in getting safely back into the air.
Commercial operations have very strict rules, there is no grey area. If the calculations are not working out you can not takeoff or land on a given runway at a given time with a given aircraft.
Have you ever been on a plane when the captain comes on the PA to announce a small delay while some cargo is offloaded to make weight ?? That is usually the reason for that.
On a particular bad winter day the A320 I was in had to circle for a while to burn off some extra fuel to make weight. Because the reported runway condition, or braking action meant that with the fuel the Captain had added over the FAA requirement, we were not within the parameters.
I don’t see why thrustreversers should only be used on contaminated runways.
In all cases, use of the reversers will help to prevent the wheels and brakes from high temperatures and also wear and tear.
The only exception in my opinion is if there’s plenty of runway length
On my local airport ( EHTE), the runway length is 1199 meters ( 3933 ft) and is mainly used for GA operation.
Also in use by small business jets, such as a Cessna Citation.
Although it’s allowed to take off and land, it’s close to it’s limit.
I sometimes see it depart and I wonder what would happen if just before V1 the pilot(s) decide to abort the take-off.
Yes, there’s some grass on both sides but close by also a wet ditch, barbwire and roads
Reverse thrust will certainly save on your brakes and wheels in fact this is the only way Aeroflot is currently landing due to this very reason.
But the original post was about landing distances, reverse thrust is not officially considered in landing data, secondly its effectiveness on dry runways is very minimal at the risk of ingesting foreign debris for hardly any gain.
True about Aeroflot but that’s a company rule and not airframe specific afaik.
Most of their planes are Airbusses and Boeings these days.
Out of 145 planes in total, only 10 of them are Russian made ( Soechoj superjet 100-95)
Ingesting dirt is a risk but I think most paved runways are well maintained and cleaned so in the majority of take-offs and landing the risk of swallow debris is minimal.
Find the distance calculators for your plane. It will be in the POH on almost every plane. It’s a chart you plug in temperature, density altitude, weight and wind and it will spit out a distance. There will be several for different configurations I.E. 15 deg flaps w. No reverser or 15 deg w. Rev and so on. I have several printed out for a PC-6 and the x-cub and they work like a charm.
