Making Better Landings

It is often said that making a good landing comes from making good approach . This item is therefore aimed at giving a few tips on making a good approach . 

For a 3 degrees glide path on an ILS, the descent rate should be about 300ft per mile. Therefore if you was 10 miles out on approach, you should be at 3000ft above the airfield elevation when intercepting the glide path .(Heathrow would be 3080 ft as you have to add the airfield height to 3000ft). 5 miles out would be at 1500ft,

 In other words times the amount of miles to touchdown  by 300 and that will tell you what your height should be. i.e. 5 miles x 300+ airfield elevation = 1580 use the formula above should help you.

The next thing in the pilots mind is how many feet per minute on the vertical speed indicator should I descend  at ? This will depend on the ground speed of the aircraft. As a rough guide  if your ground speed on approach is 70 knots your rate of descent is 350 feet per minute. If you are going to be flying jets at approach speeds of 140 knots or 160 knots the vertical speed should be for 140 knots 750 ft per minute and for 160 knots 850 ft per minute as a rough rule of thumb . It is suggested that decision height be 200ft above airfield elevation . If you are in cloud and cannot see the runway you should not descend below decision height of 200 + airfield elevation= 280ft at (Heathrow for example) the aircraft on crossing the approach end of the runway would then have to carry out a Go Around. It is also important to scan your instruments all the time. 

The runway approach  lights can assist 2 reds to white ok,  4 whites too high, 4 reds to low. If you keep the correct speed and rate of descent, you will be correct and be able to check your height at every mile using the one mile to 300ft rule. It is also suggested that maximum runway visual range should be at least 800 metres, before an approach is made. The cloud base at least 300ft. If it is not then divert and repeat the equation again checking the weather at that airport . This is where the weather briefing reports come in useful. Everything should be corrected slowly.

 On approach charts, pilots are given an elapsed time to fly.  When the aircraft crosses the outer marker beacon the stop watch is started and if the pilot has not become visual with the runway after the elapsed time the pilot  will execute the missed approach Go Around procedure.

Note it is groundspeed here for determining the rate of descent  not airspeed. If you fly your approach at 160 knots indicated airspeed and if you had a 20 knot headwind then your groundspeed would be 140 knots . You therefore look at 140 knots on the approach chart for reference to your descent rate.
                                                                                      

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