Maths techniques

To quickly convert wind speed from m/s to kt, you can use the following rule of thumb:

kt ≈ m/s × 2

Example:

10 m/s ≈ 20 kt

Step 1 – Calculate the time:
Time = Distance / Groundspeed
→ 180 ÷ 300 = 0.6 h

Step 2 – Multiply by fuel flow:
Fuel = Fuel flow × Time
→ 2200 × 0.6 = 1320 kg

✅ You will burn approximately 1320 kg of fuel over 180 NM at a groundspeed of 300 kt and fuel flow of 2200 kg/h.

Step 1 – Calculate total endurance:
5000 ÷ 2400 ≈ 2.08 h

Step 2 – Subtract 0.5 h of final reserve:
2.08 – 0.5 = 1.58 h available before final reserves

Step 3 – Multiply by groundspeed to get distance:
1.58 × 270 ≈ 427 NM

✅ You can fly approximately 427 NM before reaching the final 30 minutes of fuel reserve.

Step 1 – Altitude to lose:
FL340 – FL260 = 8,000 ft

Step 2 – Time to descend:
8,000 ÷ 1800 ≈ 4.44 minutes

Step 3 – Distance covered at 360 kt:
(360 ÷ 60) × 4.44 ≈ 6 × 4.44 = 26.7 NM

Step 4 – Add the 10 NM buffer:
26.7 + 10 = 36.7 NM

Arrondi : 37 NM

✅ The descent should begin approximately 37 NM before the waypoint to be level 10 NM in advance.

Step 1 – Combine both groundspeeds:
400 + 500 = 900 kt

Step 2 – Time = Distance / Relative speed:
1800 ÷ 900 = 2.0 hours

✅ The aircraft will cross each other after 2 hours.