and another five knots for the wife and kids?

Adding on a bit more airspeed on the approach "for safety" can often be distinctly dangerous.
reproduced from GASCO

Watching single engine aeroplanes landing at a large airport can be really quite depressing sometimes. All too often they arrive over the threshold far too fast and eventually make contact with the runway some 500 m or more into it after an extended and porpoising passage at varying heights above the surface while the pilot waits for the excessive speed to decay. Sometimes they do not wait long enough and allow the aircraft to touch down nosewheel first, which is never a good idea. Sometimes the pilot prolongs this anxious expedition just above the runway even further by failing to deploy sufficient flap or forgetting to close the throttle fully. Add in a bit of a crosswind and the antics of the overstressed pilot during this drawn out and apprehensive journey from threshold to touch down can be quite eye catching.

For single engine aeroplanes, the practice of adding on a bit extra airspeed "for safety" is generally a bad idea. It imposes extra demands on the pilot at the round out, it invites "wheelbarrowing", caused by touching down too soon and it tends to form a very bad habit that may become dangerous when the pilot has to land on a relatively short runway.

the wheelbarrow

The correct approach speed is probably specified in the aircraft's Pilot's Operating Handbook (POH) and this speed, not five knots more, is the speed you should aim for. The more comprehensive POH will offer a range of speeds depending upon configurations and how close to Maximum All Up Weight the aircraft happens to be. If the POH gives no guidance, the classic approach speed for an aeroplane is 1.3 times the stalling speed, and by `stalling speed' is meant the stalling speed in the approach configuration and at the actual weight for that particular approach. A small increase in approach speed may be specified in the POH for gusty conditions and some increase in the approach airspeed here is sensible, but only in moderation.

A common recommendation seems to be to add on to the normal approach speed half of the amount that the gusts are exceeding the general wind speed at the time. Thus, if the reported wind at the threshold is 15 KTS, gusting 25 KTS, the recommendation would suggest an addition of 5 KTS to your approach speed. This increase should however, only apply to the headwind component of the surface wind. Unless the POH specifically recommends otherwise, there is no need to add anything for a crosswind.

Having established the aeroplane at the correct approach speed and configuration, in trim, the POH may recommend a lower `threshold' speed (sometimes called VREF although that is the intended speed for a commercial aeroplane at a height of 50 feet above the threshold). Any deceleration required should take place in the final stages of the approach.

After crossing the threshold, the speed should be allowed to reduce during the `round out' or `flare'. This in essence is a period of level flight just above the runway, in which the pilot progressively adjusts the pitch attitude as the speed reduces, until the correct landing attitude has been achieved. He should then hold that attitude to allow the aeroplane to settle onto the runway. If the correct threshold speed has been achieved, float is kept to a minimum and the aeroplane will settle comfortably shortly after crossing the threshold.

Just the right speed for touch down for a single engine aeroplane such as this Pulsar. More speed means more difficulty

You may have used a takeoff and landing performance calculator thinking that it is good for any landing speed. I am afraid that calculating whether you will have sufficient runway for your landing will be useful only if you stick to the correct approach speed. If you commonly adopt an approach speed higher than the recommendation and then touch down 500 m into the runway, you had better either mend your ways or add 500 m on to the "landing distance required" calculation.

If you let the speed get too low on an asymmetric approach in many twins, and then try to recover by increasing the power on the good engine, the consequences can easily be fatal

A recent accident report demonstrated convincingly what might happen if the false idea that a higher approach speed leads to greater safety is adopted. The owner pilot of a relatively new Cirrus SR22 had to land at a strange airfield. In his report he says, I knew I was going to have to land a little faster than normal because of gusty winds. We do not know how much extra he added but his report continues, ...nearing landing and at treetop level ... I encountered a wind gust ... that made me add power.

When I had recovered, I had picked up about 5-10 KTS of more airspeed. The report then describes how, following touch down, the pilot was unable to stop in time and ended up in a fence with a substantially damaged aeroplane. While I may have misunderstood what went on here, it does seem to me that what was at the heart of the problem was the concept that more power and more speed were always the required answer to a sudden gust. Of course, if the pilot encountered a lull in the wind speed, sensed the approach of a stall and/or saw that the airspeed had reduced, then more power and more speed would have been the appropriate response.

But he had already added some extra speed and a gust could just as easily have added even more to his airspeed as reduced it. The essential point is that the pilot needed to be practised in slow flying (as we all need to be) to attempt a landing in gusty conditions. He had already added something to his approach speed and what he needed to do beyond that was to be extra sensitive to airspeed and the feel of the aircraft and to make power and pitch adjustments appropriate to what the ASI and the feel were telling him. If these told him that the gust had increased his airspeed, then an increase in power would have been quite the wrong response.

Based upon the limited information available to me about this American accident, I cannot be sure whether the pilot was actually at fault in any particular; he probably wishes now that he had thrown away this taxing first approach and gone around for a less stressful second attempt.

Reggie Bender always adds another 10 KTS, just in case

Never forget that during any approach or any other time when flying slowly and close to the ground, your airspeed is always the vital factor and whatever the other distractions, you must monitor the airspeed constantly. Let the airspeed get too low, and you may stall and spin. Let it get too high and you will face all the problems described above. The only safe policy is to adopt a speed that complies with the POH or, failing that, the classic rules described. Having chosen your target speed you must then make quite sure that, regardless of any distractions that may arise, you continue to aim for that speed. That will match the interests of the wife and kids far more closely than automatically adding on another five knots.

Nigel Everett