ENJOY YOUR CROSSWINDS!

I entered the Air Force in May 1943, and throughout our Tiger Moth and Harvard training we never received any actual crosswind tuition, as in both cases at Harewood and Woodbourne the airfields were just large grass fields, with all take-offs and landings made directly into-wind, in accordance with a “landing tee” in the signals square, as some readers may recall. It was impossible to physically teach crosswind training in view of the high traffic density – with most of our 355 Tiger Moths being based at Harewood, Ashburton and Taieri, and most of our 202 Harvards based at Woodbourne!

Another aspect of Air Force training in the early years of WW2, was that initially our RNZAF fighter pilot training was in preparation for flying Spitfires and Hurricanes in Britain, where such operations were mainly conducted from large grass airfields – whereas for those of us who later flew operationally in the Pacific, virtually all operations were conducted from runways.

With the higher landing speeds of the Kittyhawks at Ohakea and Corsairs at Ardmore, both with multi-runways, I never experienced any real crosswind problems until the day of my 5th flight in a Corsair at Ardmore, flying NZ5357, with only 202 hours P in C in the logbook! I was sent on an oxygen climb to 35,000 ft along with three other pilots –  but just failed to reach 40,000 ft – chickening out at 39,500 ft due to a fear of a stall/spin situation, with recovery unlikely due to the rarefied atmosphere – until flying at 40,000 ft across the Tasman 62 years later in a Boeing 737-800!

Returning to Ardmore from our height climb, along with the other three aircraft about an hour later we discovered that runway 21 had been closed due to maintenance so were instructed to land on runway 25. However the wind had backed to a 20-25 kt southerly, giving almost that amount of crosswind on runway 25!  All in the same boat, we all had problems after touchdown, overshooting due to potential ground loops, so after about 4-5 attempts the contractors’ vehicles were cleared from runway 21 on which we then landed without too much trouble.  For my next 2½ years flying Corsairs daily at Ardmore, in the Pacific, and Japan, I never experienced any crosswind problems of note, so was discharged from the Air Force in March 1947 still without any real crosswind training.

Fifteen years later I arrived at Ardmore late 1962 to work in the Control Tower with Vic Roberts and Howard Monk, both ex Air Force pilots, after obtaining my Air Traffic Controller’s rating at Hamilton.

Soon becoming keen to get back into the air again, after watching others flying every day, I did some flying in Piper Cubs at the Auckland Aero Club, then Cessnas at Jim Bergman’s Auckland Flying School based just below the Control Tower.  I obtained my C Cat Instructor rating in 1964, then decided to open my own Flying School in 1966, holding a B Cat Instructor Rating, using mainly Piper Cherokees, and generally a Piper fleet. My belief was that we could obtain high aircraft utilisation by using the new Cherokee 140’s as both a basic trainer, and also a four-seat private hire aircraft.

Our flying school was named Manukau Flying School and we commenced operations on 15th January 1966, on my 41st birthday. Our first brand new Cherokee 140, ZK-CNN exceeded our expectations by achieving 3046 hours by its second birthday, possibly a New Zealand record for a light aircraft??

Even though holding a B Cat instructor rating, I had still never received tuition in crosswind landings, and possessed no crosswind skills apart from the common crab, kick straight and ‘hope for the best’ method.

During the 60’s-70’s some excellent American training manuals became popular, and I learnt much from those produced by William Kershner and published by the Iowa State University Press. I learnt and adopted a number of methods expounded by him in his various manuals, and one in particular was a positive approach to crosswind challenges. As he explained, there are two methods of counteracting drift during a crosswind approach and landing, and the most effective method is a combination of them both. They are called the crab method, and the wing-down method. Each provides a horizontal force opposing the horizontal force created by the crosswind. As he claimed, a combination of both methods can substantially increase ones ability to successfully cope with stronger crosswind conditions. With wings level there is only a vertical component of Lift, but by banking you can also create a horizontal component of Lift, relative to the degree of bank applied. This can be utilised to either totally or partially counteract the drift effect of the crosswind – both during the approach, and throughout the landing, by slight changes of tilt/bank angle using the ailerons. During my approaches in crosswind conditions, as an instructor my mind always pictured this adjustable horizontal component of lift, just as originally taught on blackboards! By adjustable I mean as required to maintain runway centreline until touchdown – by adjusting the tilt or bank angle.

Factors

  • Commencing with the crosswind approach, always be one step ahead of your aircraft and the situation!

  • Throughout the final descent the strength of the wind, and therefore the crosswind component, and correction required, normally reduces as altitude reduces, but to complicate things, if the approach speed also reduces, that increases  the drift factor, which tends to compensate.

  • Even a few miles out, with wind information received on ATIS, positively tilt your aircraft very slightly “into-wind” by 2-3° on the A/H, which is creating no risk at all, and is not apparent to the passengers. By tilting the aircraft very slightly “into-wind”, the crab angle can be considerably reduced, with less correction required later on. Conversely any slight inadvertent tilt of the aircraft the wrong way, i.e. “downwind”, substantially increases the required crab angle necessary to remain on centreline, which will never happen if you consciously and positively tilt very slightly “into-wind”.

  • One could say, with perhaps a little exaggeration, that by tilting slightly into wind, it halves the amount of crab required, whereas by tilting slightly downwind doubles the amount of crab required – to remain on centreline.

  • A good example of this was demonstrated by a candidate on my 596th and very last PPL flight test in 1993. I note that his aircraft registration was not one of ours, so he had apparently trained elsewhere. His flight-test was up to standard in all respects, until finally coming into land on runway 21 at Ardmore with a southerly wind blowing from our left. Although approaching on runway 21 his D.I. was reading 180° – heading 30° into wind, and to the left of the runway direction. He was tilting slightly the wrong way! – but I decided not to distract his attention so wrote 180° down on my pad, to discuss the situation later.

Over 30 years of flight instructing I observed hundreds of pilots making cross-wind approaches, and I noted that if allowing for a crosswind from the left they would approach aiming into-wind to the left of centre-line, but in relatively slow light aircraft the crab angle was such that their forward vision was to the right of normal, and some would tend to inadvertently slightly tilt the aircraft that way – slightly downwind! – possibly to get a better view ahead. Similarly, if allowing for a crosswind from the right they would approach aiming to the right of centreline, but looking forward to the left of normal, and inadvertently tilting slightly to the left – again slightly downwind! This inadvertent situation requires more crab allowance to maintain centre-line during the approach than necessary, and therefore more correction in the final stages of the approach.

Recommended Technique

  • Although not absolutely necessary from the commencement of the final stages of the approach to hold a few degrees of tilt “into wind”, it does positively prevent any inadvertent tilt the wrong way, thus keeping one step ahead of the situation. Also, holding a slight amount of opposite rudder to reduce the crab angle and maintain centre-line does give the pilot some feel of the rudder at that stage.

  • I would continue to hold the centreline by maintaining a slight(nominal) tilt “into-wind”, but gradually reducing the crab angle with rudder as the wind strength gradually reduces with altitude, until in the final stages the crab angle is zero, and the slight tilt sufficient to counteract the reducing cross-wind effect.

  • I would consciously bring the nose straight at 2-300 feet above the runway, and thereafter maintain centreline with only slight bank changes, making it quite simple to touch down with one’s wheels on either side of centre-line, and the aircraft pointing in the correct direction. If the nose is held straight during the final stages of an approach, and the aircraft maintained on centre-line by slight bank changes – the angle of bank therefore must be correct for the amount of drift being experienced – with no guesswork whatsoever.

  • With light aircraft – up to light twins including my favourite Cessna 402 model, this permits one to do a normal hold-off landing, similar to what one would do in light or nil wind conditions, but also with crosswinds in excess of 15 knots and up to a good 20-25kts reported crosswind component. Many pilots I have flown with used the technique of merely holding a crab angle, then  “kicking straight” at the last minute, then massively overbanking into wind immediately prior to touchdown – resulting in a virtually uncontrolled ‘arrival’ not at all encouraging to passengers, or good for the tyres! In fact during the action of “kicking straight” the yawing effect can cause the into-wind wing to rise, which is exactly what you don’t want it to do!

  • At many airfields, low obstructions around the airfield can cause a noticeable reduction of wind strength during the final few feet, below windsock level, easily correctable by reducing bank slightly, but it is amazing how so many pilots still maintain a far too steep a bank angle at this final stage – quite unnecessarily! I found that right at ground or runway level the degree of tilt necessary as shown on the A/H was only about 5° even for crosswind components of up to say 15kts. That can be rectified by merely adjusting the bank angle sufficiently to maintain runway centreline, which is quite simple.

  • Assuming a tricycle undercarriage aircraft, hold the nosewheel off until loss of airspeed causes the aircraft to sink gently onto the runway in the normal way, holding the nose straight with the rudder pedals. Then wind the control wheel fully into-wind and slightly forward. This will probably increase aerodynamic drag on the downwind wingtip utilising aileron drag, helping to reduce weathercocking effects – depending on the “Aileron Drag” compensation design features for the aircraft type. Moving the control column/wheel lightly forward ensures that the aircraft doesn’t inadvertently lift off again under strong gusty conditions.

  • Using the above technique over many years, I regularly taught crosswind landings with no difficulty in both high-winged Cessnas, and low-winged Pipers, with reported crosswind components of 25 to 30 knots, amusingly on some occasions in the course of ILS approaches during Instrument training, when international and internal airliners have been diverted due to conditions!

Tailwheel aircraft

Being involved in both types, I experimented with Piper Cubs, Cessna 180’s and other tailwheel types, and discovered that even using Ardmore’s sealed runways, as well as the grassed areas, these tailwheel types could be comfortably and safely landed in up to 10-15 knots of reported crosswind component, using the same wing-down, hold-off, method as for our tricycles, or as for a normal tail-wheel three-point landing – but landing on two points! – which doesn’t create any real problem as undercarriages are built to withstand five times the weight of an aircraft. However with above 15 knots reported crosswind component I would, like most pilots, do wheel-landings, but still wing-down as depicted in the illustration of Piper Cub ZK-BKV.  BKV was the first aircraft I flew, at Mangere in 1956, after a nine year break following my last Corsair flight in Japan in 1947! – a frightening experience, and without a parachute! I purchased ZK-BKV in 1973 for tail-wheel training at Manukau Flying School – and it is now owned and operated by Ace Aviation at Masterton. Old soldiers never die!

Remember, even in strong crosswinds it is easy to maintain positive control of your aircraft right down till touchdown – so enjoy your crosswinds!  – without them life would be boring!

Only a few days ago, meeting a friend arriving at Tauranga airport from Wellington in a Dash 8 Bombardier, I was pleased to see the pilot making an immaculate crosswind landing, apparently using the technique I describe above!

Bryan Cox

Tauranga

Click on photos to enlarge