Most aircraft accidents occur during the takeoff and landing phase of the flight. Collisions with obstacles during climb out, runway overruns on landing occur too often. On this part of the site we will take a look at the various factors contributing to the performance of the aircraft in this part of the flight. Hopefully we help the pilot ensuring safe operation during these phases of the flight as the rules require that of the pilot in command.

The effect of wind on our aircraft is something we can influence to some extend. We can choose runways (when the airport has multiple) and use the wind on our tails when going to our destination. Wind can also vary with altitude so option that can be used too.

Performance Factor, Headwind

Aircraft use the flow of wind over the wings to generate lift to be able to fly. A minimum amount is required to liftoff and usually the engine generates power to obtain this liftoff speed. By taking off into the wind (the wind generates part of the lift) the aircraft lifts off sooner and this will result in a lower ground speed and therefore a shorter take-off run for the aircraft to become airborne. It is therefore recommended. Not only for safety reasons: a takeoff that is abandoned will also use less runway to stop because ground speed is lower. Climbing into the wind will result in a steeper climb, great for clearing obstacles in your path.
Landing into the wind has the same advantages, it uses less runway, ground speed is lower at touchdown (less wear and tear on the aircraft) and the runway is available sooner for the next aircraft when it gets a bit crowded.

A rule of thumb says that takeoff and landing distances are reduced 1,5 % for each knot of headwind up to 20 knots.

Performance Factor, Tailwind

Takeoffs with a tailwind will result in the use of much more runway to get enough lift for flight (It takes distance to nullify the tailwind before any headwind is obtained for lift). Climb angle is also reduced. Think obstacles! A five knot tailwind increase takeoff distance with 25% and a ten knot tailwind with 55%. The same can be said about landing distances. Reasons for doing tailwind operations are noise abatement procedures and in case of certain mountain airports where you land up slope and takeoff down slope again.
Landing with a tailwind has another problem: you will approach the runway with a higher ground speed and this could lead the pilot into lowering his airspeed because he/she is accustomed to a lower ground speed. At this point a stall can happen. Just fly your usual final approach speed and all is well.

Best thing to do is to avoid tailwinds altogether (except when flying), only if sufficient runway is available it can be done safely. Tailwinds do not lower the indicated airspeed or stall speed of the aircraft, they influence the groundspeed.

Performance Factor, Crosswind

Only when there is no wind, exact headwind or tailwind, the crosswind is no factor. During take off and landing the crosswind can be difficult to handle, and they are not always available to practice. Never exceed the demonstrated crosswind for your aircraft, if you do you will become the test pilot..

Handling a crosswind during landing can be quite a task, especially for new pilots. Basically there two methods for approaching a runway with a crosswind: Crab into the wind and the Wing down/slip method.

I prefer the crab method, it's easy to do, just fly to the runway. If this can not be done then its time to divert to a more favourable runway/airport.
The aircraft does not slip (important when fuel levels are getting low), all available stick/yoke control for counteracting turbulence is available and you and the passengers do not lean sideways. Everybody sits comfortable. The difficult part could be when landing: Line up the aircraft with the runway and bank into the wind during touchdown, while the speed reduces. At this point the aircraft switches to the wing down situation and at almost the same time touchdown is accomplished. Remember to keep the stick/yoke into the wind during roll out.

The wing down/slip method requires the pilot to fly the aircraft lined up with the runway and banked into the wind when turning on final, at this point the aircraft slips and in a slip stall speed is higher. Some find this the easy way. But if turbulence is encountered, stick or yoke control could possibly be not enough to control it. At this point you will be blown away from the center line and might have to abort the landing. You and the passengers lean toward the side as does the fuel in the tanks. This could not be comfortable for them. The landing is the same as the crab method.

Crosswind Chart

Crosswinds reduce your headwind component (only when the crosswind is more or less from up front). Some rule says if crosswind is 30 degrees off the runway heading it reduces the headwind by 15 %. At 45 degrees it will be 30% less headwind. Something to keep in mind when heading for short runways.

Crosswind calculator chart
To calculate the crosswinds for take off, landing and enroute: click here for the standard crosswind chart.

Performance Factor, Gusting Wind

During gusting winds it will be required that you keep the aircraft on the ground somewhat longer to provide a higher margin from the stall. During landing you must add half the gust factor to your final approach speed. It is wise to do the same on take off. Add half the gust factor to you normal lift off speed, this should provide a safe margin. Keep in mind that because of these higher take off and approach speeds a longer roll on the runway is needed.

Performance Factor, Surface condition

An uphill runway increases the take off run and a downhill runway increases the landing roll. A up slope of 2% adds 15% to your take off distance and a down slope of 2% decreases it by some 10%. So everything else being equal: take off downhill and land uphill. It as simple as that. Be prepared that local rules might require otherwise.

Grass, snow or soft grounds increase the rolling friction and ground runs will take longer than on paved runways. Dry grass can increase take off runs by some 15%. Long wet grass can increases this number again depending on the length of the grass and how wet it is. Aircraft wheel size is also important. The type of aircraft can play a role too.

Taking off in long wet grass on a short runway could not be advisable. Even more so when puddles of standing water are present shortly after a rain shower, acceleration through water is very sluggish.

Landing on such a runway can increase the ground roll due to the fact that the brakes are not as effective as on a dry runway. Grip of the tires on wet grass is much less, on long wet grass it could mean a very large increase of ground roll.