Position Points

Question 1

What is the definition of equitime point (ETP)?

Answer 1

POINT where it takes EQUAL TIME to fly to either a PAIR of ALTERNATES UNDER a given set of CONDITIONS;
The pair of ALTERNATES MAY or MAY NOT on TRACK

Question 2

Why do we calculate ETP?

Answer 2

Allows us to QUICKLY DECIDE which of chose ALTERNATE airfields is CLOSEST in TIME if there is any NON-NORMAL CONDITIONS

Question 3

When may ETPs become essential?

Answer 3

ENGINE FAILURE;
DEPRESSURISATION;
MAJOUR SYSTEM FAILURE;
ILLNESS ON BOARD

Question 4

What does the term ground speed OUT refer to?

Answer 4

GROUND SPEED at which the aircraft TRAVELLED TO the POINT at which EVENT TOOK PLACE

Question 5

What does the term ground speed ON refer to?

Answer 5

The GROUND SPEED to PROCEED to the DESTINATION at the TAS and the WINDS at revised altitude (if any) under NON-NORMAL CONDITIONS

Question 6

What does the term ground speed HOME refer to?

Answer 6

The GROUND SPEED to travel BACK to the DEPARTURE aerodrome at the TAS and the WINDS at revised altitude (if any) under NON-NORMAL CONDITIONS

Question 7

What ground speeds do we use to calculate distance to ETP?

Answer 7

Both ground speed ON and HOME;

NON-NORMAL CONDITIONS are used

Question 8

What ground speeds do we use to calculate time to ETP?

Answer 8

Ground speed OUT;

NORMAL CONDITIONS are used

Question 9

What may ETO also be referred to as?

Answer 9

CRITICAL POINT;

POINT OF EQUAL TIME (PET)

Question 10

What are the points and distances represented in ETP?

What do they mean?

Answer 10

D - Total distance;
X - Distance from CP to A;
D-X - Distance from CP to B;
H - Ground speed HOME from CP;
O - Ground speed ON from CP

Question 11

What is the formula that represents ETP?

Answer 11

X = D x H / O + H

Question 12

What is the formula that represents ETP time?

Answer 12

T = X / G/S OUT

Question 13

What does ETP(N) represent?

Answer 13

All engine ETP

Question 14

What does ETP(1) represent?

Answer 14

SINGLE engine FAILURE on a TWIN engine aircraft ETP

Question 15

What does ETP(3) represent?

Answer 15

SINGLE engine FAILURE on a 4 engine aircraft

Question 16

What does ETP(D) represent?

Answer 16

DEPRESSURISATION FAILURE ETP

Question 17

What does ETP(1D) represent?

Answer 17

ONE engine DEPRESSURISATION on a TWIN engine aircraft

Question 18

What does ETP(3D) represent

Answer 18

ONE engine DEPRESSURISATION on a 4 engine aircraft ETP

Question 19

How much fuel should an aircraft ideally carry?

Is this practical? Why or why not?

Answer 19

SUFFICIENT FUEL for a RETURN flight from DESTINATION TO DEPARTURE aerodrome;
NO, in order TO CARRY more fuel, more fuel must be BURNED, it also REDUCES commercially valuable PAYLOAD, CHANCE of DIVERSION is LOW

Question 20

What is the definition of point of no return (PNR)?

Answer 20

The MAXIMUM DISTANCE outboard an aircraft can travel EN-ROUTE and RETURN to the DEPARTURE aerodrome, ARRIVING overhead with specified FUEL RESERVES WITHIN the constraints of its SAFE ENDURANCE

Question 21

When must PNR be calculated?

Answer 21

When an ISOLATED DESTINATION aerodrome has NO SUITABLE ALTERNATES for the aircraft to DIVERT to in case it is NO LONGER FEASIBLE to land at DESTINATION

Question 22

When are PNRs essential?

Answer 22

MARGINAL WEATHER at DESTINATION;
ENGINE FAILURE;
DEPRESSURISATION;
ILLNESS ON BOARD

Question 23

What does it mean if you have crossed your PNR?

Answer 23

You are COMMITTED to LANDING at that aerodrome

Question 24

What are the points and distances represented in PNR?

What do they mean?

Answer 24

E - (Fuel on board / fuel flow) - (mandatory reserves / fuel flow);
O - Ground speed OUT;
H - Ground speed HOME;
D - Distance to PNR;
T - Time to PNR

Question 25

What is the formula that represents PNR?

Answer 25

D = E x O x H / O + H

Question 26

What is the formula that represents PNR time?

Answer 26

T = E x H / O + H

Question 27

What effect does wind, fuel and speed have on PNR?

Answer 27

NIL WIND: Gives MAXIMUM PNR DP;
ANY WIND: Reduces the PNR DP;
MORE FUEL: INCREASES PNR DP;
GREATER SPEED: INCREASES PNR DP (when all other factors are constant)

Question 28

What is the definition of point of safe return (PSR)?

Answer 28

.

Question 29

What is the definition of last point of diversion?

Answer 29

A PNR DO calculated to ARRIVE over the LAST EN-ROUTE ALTERNATE available with FUEL EQUAL to the specified RESERVES

Question 30

What is the derived formula for PNR including the wind factor?

Answer 30

D = (E x TAS / 2) - (E x W^2 / 2 x TAS)