Climb Gradients

Aircraft normally should take off into wind. This gives the best climb gradient over the shortest distance. As the aircraft gets higher, the wind is stronger. This gives a much better  rate of climb over the distance, than an aircraft taking off  with a tailwind. In a tailwind take off the distance is increased across the ground. 

On average the wind is double the speed at 2000ft than the surface wind. The surface wind is slowed by friction. The wind may also be from another direction where it could have been  deflected. Be very careful of valley winds during the day. They have caught some pilots outs.

Each aircraft has a best climb speed and this should  always be used after  take off until a safe height is reached. Pilots of aircraft should read the aircrafts handbook for best climb speeds. Only when at a safe height should you adopt the cruise climb. For pilots the climb gradient must be that shown in the SID charts as a minimum. Noise abatement also comes in to play here.  Remember the higher you are the less noise.

Lets look at two aircraft taking off with the same airspeed and rate of climb. The first one takes off into wind, and the second one with a tailwind.

The aircraft taking off  into wind will have traveled a much shorter ground distance to a height 2000 ft compared to the aircraft taking off with a tailwind. The climb angle would also be bettered by at least 3 degrees. We will assume the wind to be 20 knots on the ground. At 2000 ft it would be double. It is true the faster the aircraft fly's  the more lift it has, but you also have to realize the more ground  you will cover before you get to the same height.  

Lets assume the wind is a 20 knots and you take off at 140 knots. This means your groundspeed is 140 - headwind speed = 120 knots 

Now lets assume you take off with a tailwind of 20 knots at a climb out speed of 140 knots, your groundspeed now will be 160 knots 140 +20.Some airfields have minimum  climb gradients published for pilots in chart form. This will tell the pilot the minimum  climb  for the VSI and airspeed allowed for safety at different speeds. Remember a hot day and a high altitude airfield will seriously affect your climb performance. 

The best way to stay alive is to  always make sure that your  aircraft's climb gradient is quicker than the climb gradient  of the hills around you. Early signs of this going wrong is the eyeballs getting bigger and the urge to go to the toilet. Have fun but be careful especially if going into cloud. It is essential that the aircraft manual is checked and the correct speed flown. Also watch your Vertical Speed Indicator.

Below is a table for you to work out how much you climb or descent rate should be per climb descent angle published in charts. This charts is for take off and landings climbs or descents on route

The assumption is is 1 degree =100 ft per nautical mile

Most ILS approaches are 3 degrees so 300ft per mile you are required to descend.

Climb

Descent angle

Height/FT req to gain lose per NM   Ground  speed      Feet     per  

 Minute

 

   req      
60 90 120 150 180 210 240 270 300 330 360
2 200 200 300 400 500 600 700 800 900 1000 1100 1200
2.5 250 250 375 500 625 750 875 1000 1125 1250 1375 1500
3 300 300 450 600 750 900 1050 1200 1350 1500 1650 1800
3.5 350 350 525 700 875 1050 1225 1400 1575 1750 1925 2100
4 400 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400
4.5 450 450 675 900 1125 1350 1575 1800 2025 2250 2475 2700
5 500 500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000
5.5 550 550 825 1100 1375 1650 1925 2200 2475 2750 3025 3300
6 600 600 900 1200 1500 1800 2100 2400 2700 3000 3300 3600
6,5 650 650 975 1300 1625 1950 2275 2600 2925 3250 3575 3900
7 700 700 1050 1400 1750 2100 2450 2800 3150 3500 3850 4200

Charts should give you these details. But if the climb angle is greater than this you should be able to work the sequence out.  Simcharts by Jeppesen are worth buying.

Example you need to climb out on a 3 degree path. Your climb groundspeed is 210 knots your vertical climb speed needs to be at least 1050 feet per minute. terrain and obstacles may make the climb or descent gradient differ from airfield to airfield.. It is important therefore to comply with the charts For example the London City  climb gradient is 6 degrees.

This should help you make better approaches now once you know the ILS gradient on the charts. or safer in the climb out