Crosswind landings

Landing on grass strips of marginal length requires a little bit of thought for pilots. It's no different in FS2004 because a poorly executed approach is going to result in the same sad event a few minutes later. FS pilots have to learn the real world techniques for happy flying - so here's a quick crash (or hopefully, lack of it) course in staying ahead of the game.

Crash, reboot, start again.

In fact, before you do start again, take a second to work out why it went wrong in the first place. Did you appreciate the strip was short before your first horrified glimpse of it when you turned final? Did you realise that the wind would produce such a drift angle? In both cases the information was at your fingertips BEFORE YOU TOOK OFF. So, let us start the flight again except from a more professional point of view. I say this because it hasn't been entirely necessary before in FS - but FS2004 has pushed the boundaries back a lot further and, for good flying, there is a greater need to fall in with your real world counterpart and do things much as he or she does.

For the sake of this description I'll fly the Cessna 172. First it's a good plane, second it's available in FS and third I've flown many hours in them. I have both learned a lot and had a few hairy moments - in situations similar to those I am about to help you with. The bonus with using the C172 is that you've got the checklists in FS to give you correct approach speeds. These are not picked out of a hat at random, they are there to be used - and I mean both checklists and speeds.

Back at the start of your flight you have two sets of information. First you have decided where to fly to and then you've got the weather. At this point take a little time to dig out the details of your landing point. It's all there in the FS Map View (and in FSNav if you use it). The two most important items you need to look for are runway length and surface. By surface I mean grass or tarmac as grass is a lot less forgiving than a decent hard runway.

Runway length must be sufficient to be able to land the aircraft. In fact I'll go one stage further than that and ask you to check that the runway length is long enough to take off in. Why? Because aircraft need a longer distance for take off than landing (you can brake on landing but there's nothing in this world apart from a rocket booster that will help you get airborne faster than your engine will allow). So, what sort of distances are we talking about that become marginal for a C172?

Here I am going to take a broader outlook because I don't wish to get involved in too much technical discussion. Landing and take off distances for all aircraft are contained in a complicated (and rather horrifying) graph in the Users Manual because there are many factors that will vary the end figure. A real pilot will have to take into account the aircraft weight, temperature, airfield altitude, wind direction and runway slope to get to the figure needed. Here I will stick with the figure given for what we call standard ISA conditions - no wind, temp +15C, pressure 1013Mb (29.92"), sea level.

The C172 notes in FS tells you that the required runway length at sea level is 960ft. That's not quite true. The figures I have (for the C172N) give a landing distance of 1250ft and a take off distance of 1525ft. Again I won't bore you with the technical definition of Take Off Run, Take Off Distance and Landing Distance but the first of these is not a practical value in the real world. Looking through the handbooks I have for other light aircraft (Cherokee, AA5, C177 Cardinal, PA24 Comanche) show similar values. Go up to an Aztec and it gives a LDA of 1500ft and TODA of 2000ft.

Therefore, treat any airfield with a runway length of less than say 2000ft (600m) as getting marginal for your flights. Why do I add the extra? Because the book figures don't take into account any sloppy flying. They assume you fly the approach at exactly the right speed and touch down right on the numbers. If you're fast or high or bounce or float you've lost the game. The little bit extra I suggest is insurance against these.

Runway 13 at Westray is 1381ft (421m) so it is a good example of trying your skills out. You could (theoretically) land there with 131ft to spare - assuming no wind. Which nicely leads us to the second part of your planning.

Having worked out if the trip you are planning is viable as far as runway length goes your next step would be to get the weather. There is no point in sitting down with your maps and flight logs and working out all your data only to get the weather and find it's too bad to fly! Get the weather first, work out your normal flight plan data (in FS just use the FS or FSNav tools) and print yourself off your final flight plan. Just wait a second - there's one more thing I'd like you to do.

Check the wind direction and speed again. From this work out the ideal runway you should take off from (the one most into wind) and the runway you'll be using at your destination. You might find yourself in a dilemma here because the longest runway at your destination may not be into wind - although a shorter one may be! Here you have to weigh up the merits of landing on a long runway with a crosswind or the short runway which may be marginal in terms of length. However - think about it now - not when you get to your destination..

OK - enough said about the pre flight. Let's look at the landing stage of the flight.

Short Field Approaches.

You've had a nice flight and now comes the final test to make it perfection - a brilliant landing (of course!).

You know that the runway is short because you did your pre flight check. You know that you are going to have to fly a short field approach. Therefore you can get this set up early on rather than do it in a panic as you turn final. The C172 handbook in FS doesn't make any reference to short field landings. All it says is "On final approach, plan for a landing speed of 65 knots with full flaps. Select a point just past the runway threshold, and aim for it.". However, the checklist in the aircraft is a bit more helpful because it says "Airspeed 60-70kts flaps down" and this gives a clue that you can get your speed officially back to 60kts. This slowest speed is a must for a short field approach. The value is correct in that it ties in with the actual C172N checklist - but the latter is a bit more explicit. It says;

Wing Flaps	- FULL DOWN
Airspeed	- 60kts (until flare)
Power	- Reduce to idle after clearing obstacle
Touchdown	- Main Wheels First
Brakes	- Apply HEAVILY
Flaps	- Retract

Apart from the bit about the brakes everything else is perfectly valid in FS. It doesn't talk you through the approach process but let's give you a bit of help in this.

First I'm assuming that you are a very good FS pilot who hasn't developed any bad habits that I would want to shout at you for. Good. I'll therefore assume that you get to any airfield and join the correct traffic pattern in the circuit. You don't do anything different for a short field approach. Fly downwind as normal and do your checks. Turn base leg, reduce power to 1500rpm and keep the aircraft level to let the speed decay to 85kts (flap limit speed). The nose will want to drop because you've reduced power but don't let it! Trim, trim, trim! - it's speed you need to kill here, not height.

Once the speed is approaching 85kts you can start dropping some flap. Of course flap will create drag and reduce your speed further - but this is the point at which you do lower the nose to keep airspeed constant. Which will almost certainly require you to retrim again. Do it - don't get lazy. Base leg is a busy part of the flight and if you do it right it makes it so much easier on final. You should end up with two stages of flap set with speed down at 70kts.

Turn final. Line up on the centreline and then put down full flap. You'll see the speed drop again but don't let it get below 60kts - again try and stop the nose from dropping by holding it up with the stick and then trim out the forces. You will probably need more power at this stage to overcome the drag of the large flaps. Settle the aircraft down into a nicely stabilised approach so you can concentrate on the landing. If you find you can't do this then the trick is to go further downwind next time to give yourself a bit of extra room.

Right - you are now on finals with full flap down, speed steady at 60kts and the aircraft trimmed so that you could take your hand off the stick. Do so - it's what my old instructor used to ask me when he thought I was being lazy! By now you can see the threshold and should be able to judge your approach to it. You are working to more finite limits here so don't be sloppy - concentrate. You've got to get the aircraft down right on the threshold and this is what you should be looking at. Keep checking your speed and height all the way down. Now the trick:

Above all keep a beady eye on that threshold and act instantly if you look as if you are going to land short or long. Keep working at this right up to the point of touchdown.

As soon as you are over the runway don't try for a nice dainty landing - flare and let the aircraft touch down. Instantly chop the power (you can do this a second before touchdown if you know you are inches off the ground - not feet!) then brakes hard on, get the flaps up (reduces lift so gets more weight on the wheels) and keep your fingers crossed.

At ANY point in the approach if you find things going wrong then give it up. Go around for another try. With a big runway you've got a bit of time to sort things out and can afford to land a bit further down than normal. With a short field you don't have any such luxury - everything has got to be spot on.

A final note. Don't use PAPI's for the approach as they are set at a 3 degree angle. This is too shallow for a light aircraft and you would need a lot of power to maintain the shallow descent. Light aircraft have a steeper descent profile - around 5 degrees.

Crosswind Landings

You've got onto final approach and this time you find it's the wind that is not being kind to you. Instead of pointing right down the runway it's blowing hard from way off to one side. To make matters worse it may also be blustery as well. These conditions tax any pilot so if you don't like them welcome to the club. However, you're up there and a good landing is needed before your first pint - so let's see the way to do it.

A crosswind landing isn't any different from a normal one except that you aren't pointing at the runway. Don't panic, stay calm and do what you normally do on any approach (OK so if you normally don't stay calm and you do panic don't change the habits of a lifetime just for me then). You don't add lots of speed on final - that may make the approach better but it's going to come back on you in spades when it comes to the actually touchdown.

The one thing you do do is go easy on the flaps. To quote Cessna's C177 manual - "When landing in a strong crosswind use the minimum flap setting required for the field length.". In the C172 you should never use full flap and I don't recommend just one stage either - that's providing more lift than drag and it isn't going to help. It's either two stages of flap (the 20 degree setting) or no flaps at all. Don't be timid about a no flap approach if needed - but try these out on a calm day first so you get used to the slightly different handling of the aircraft. Also keep in mind that flaps reduce stall speeds and allow you slower approach speeds too. If you use no flaps in a crosswind don't try to fly the approach at the flap down speeds or you'll be in deep trouble. 70kts is good flaps up, 65kts at the minimum.

Having turned final and sorted out your flap settings the next step is something you individually will have to decide upon - the approach technique. What you are going to have to do is stop yourself from drifting off the runway centreline. There are two methods to a crosswind approach - the crab method and the wing down method.

The more widely used method is the crab approach. On this type of approach you point the aircraft into wind slightly so that the drift angle is matched by your offset heading. It takes a bit of practise - and the views in FS make it slightly harder than in real life. Finding the right angle is just a matter of experience. Once you get this right you'll fly right down the centreline to touchdown. In real life it isn't so easy - winds decrease as you descend and the drift angle is constantly reducing so you have to keep working at the approach.

The approach using the crab method is quite easy. The tricky bit is the landing. The problem is that you have to keep the drift angle maintained right up to the instant of touchdown. The second you turn the aircraft's nose onto the runway heading you will start to drift off towards the downwind side of the runway. You can see the dilemma - if you keep drift on at touchdown you'll damage the landing gear and will almost certainly find the aircraft will swing rather sharply. Kick the drift off that fraction too early and you'll drift off to the side of the runway - and again any touchdown will be made with the aircraft pointing in one direction but moving in a different one.

The only right way is in split second timing - you have to kick the drift off at the instant you are going to touch down. Again I would say that it's easier in real life because you have the more sensory input - but in FS you aren't going to do the same amount of damage if you get it wrong! How long have you got between kicking off the drift and touchdown? It's hard to say but I would say only a second. By two seconds the wind has started you moving sideways.

Option number two is the wing down method. Now you all know that dropping a wing causes the aircraft to turn. In fact that's not strictly right. As you apply aileron the aircraft will bank (roll) - it's secondary input that starts a turn. If you roll the aircraft slightly in one direction and leave it there the aircraft will actually sideslip. It's hard to describe this because you don't feel it and you don't see it - unlike most manoeuvres. However, the aircraft will sideslip - it slips towards the lower wing. The amount of sideslip is determined by the angle of bank. If you leave any sideslip on for more than a few seconds things change. The slip will become a turn because of the side pressure on the fin and rudder - and to stop turning you need to add a little opposite rudder.

Getting back onto final again you line up with the runway - but this time you lower the wing that's into wind. Again, by a matter of trial and error, you find a bank angle that will cancel out the drift caused by the wind - you are effectively sliding into the wind at the same rate as it's blowing you off the runway centreline. You also need a bit of opposite rudder to stop the aircraft from turning into wind. Now, landing from a wing down approach is a lot more civilised because you can keep the bank on right to touchdown. Yes, you'll land one wheel first - but that doesn't matter.

The only word of caution is that you must remember the type of aircraft you are flying when making this type of approach. For singles there is no problem but if you are flying a twin with marginal prop clearance from the ground it isn't such a good idea. This is why underslung jets like Boeings and Airbus aircraft never use the wing down method - it is all too easy to scrape a pod on touchdown.

The choice of approach technique is really up to you. Some pilots just can't get to grips with kicking off drift and go for wing down approaches. Others find that the wing down method is easier but it's uncomfortable flying in that manner. Again, from the C177 manual, "Although the crab or combination method of drift correction may be used, the wing down method gives the best control."

Finally a quick word about turbulent approaches. All the above still applies but here you have to be a bit more careful with speed control. Needless to say that the approach itself is going to be a handful all the way down and that any attempt to crack the drift problem is one of continual readjustment. The secondary problem with gusty conditions is that the air you are moving through changes velocity all the time. If you get hit with a gust your speed will rise, you'll get more lift, the aircraft will go up. If the gust dies you'll have a drop in airspeed, less lift, you'll go down. You can end up fighting the approach all the way - trying to stay on the centreline with continual rudder or aileron adjustments and trying to fly a normal descent profile with constant elevator and throttle corrections.

Now all this is damn good fun and I would recommend it to anyone who has let the cobwebs of life slowly drift over them. The really exciting bit is the touchdown. You are busy trying to kick off the drift angle just as the aircraft is about to kiss the tarmac - and you get hit by a gust. Next thing you are ten feet up as if perched on a podium wondering what is going on. Then the gust dies, you lose all your airspeed and down you drop.

For this reason pay attention (yes I know it's been a long and boring bedtime story) to the reported wind - especially the gust strength. If the wind is reported as 240 at 25 gusting 35 kts then halve the gust amount and add it to your approach speed. This will ensure that you have a bit in hand during the approach and that a gust that drops on you doesn't leave you too near the stall.

If you have Excel I have created a spreadsheet that will provide crosswind component data. Enter your track, TAS and wind and it will give you drift angle, crosswind speed and groundspeed.

Short Field Approaches
and Crosswind Landings

Getting Outside the Comfort Zone

Crash, reboot, start again.

Short Field Approaches.