Enroute diversion calculations Flashcards
PNR
Point of no return, it is the point along the track which the a/c would not be able to return to its departure point using the fuel it has on board excluding its legal reserves, it can either be calculated as time to PNR or Distance to PNR
What will your PNR be if there’s in nil wind
At half your endurance
Time to PNR Equation
E / (O+H) = PNR / H
- E = endurance
- O = G/S out
- H = G/S home
Time to PNR nav computer calculation
- E on outer scale aligns with (O+H) on inner scale
- PNR on outer scale aligns with H on inner scale
PNR how to work out H and O
- O (G/S out) is the TAS with the wind component added
- H (G/S home) is the TAS with the wind component subtracted
Note: the wind component will already have a + or - sign so take this into consideration when subtracting/adding
PNR/ETP wind component
- Tailwind = +W.C
- Headwind = -W.C
How to work out distance to PNR
Calculate time to PNR and then apply G/S out to the time (using speed, distance time nav computer calculations)
ETP or CP
Equitime point or critical point is a point along a track where it takes equal time to either continue on to destination or to return home from departure airfield
Importance of knowing ETP/CP
In the event of an emergency the ETP point gives the pilot the quickest airfield to return to
Distance to ETP equation
D/(O+H) = ETP/H
- D = distance of leg
- O = G/S from ETP to destination
- H = G/s from departure to ETP
Distance to ETP on nav computer
- D on outer scale aligns with O+H on inner scale
- ETP on outer scale aligns with H on inner scale
ETP calculating O
The sector 2 wind component is applied directly to TAS
ETP calculating H
The sector 1 wind component is applied in the reverse to TAS
