 # How to Calculate Distance and Time to the Point of Equal Time and How to Calculate Time and Distance to the Point of Safe Return

## Calculating distance and time to the point of equal time (PET)

### Distance to the point of equal time (DPET)

To calculate DISTANCE to the point of equal time (DPET) you need:

1. the total distance from your point of origin to your destination (D)
2. your ground speed home (GSH)

#### Example

1. 560 NM (D)
2. 180 KTS (GSH)
3. 220 KTS (GSO)

DPET = (D x GSH) / (GSH + GSO)
DPET = (560 x 180) / (180 + 220)
DPET = 252 NM from your point of origin

### Time to the point of equal time (TPET)

To calculate TIME to the point of equal time (TPET) you need:

1. distance to point of equal time (DPET)

#### Example

1. 252 NM
2. 180 KTS

TPET = DPET / GSO
TPET = 252 / 220
TPET = 1 hour 24 minutes from your point of origin (1.4)

## Calculating Time and Distance to Point of Safe Return (PSR)

### Time to Point of Safe Return (TPSR)

To calculate TIME to the point of safe return you need:

2. your ground speed home (GSH)

#### Example

1. 5 hours
2. 180 KTS
3. 220 KTS

TPSR = (E x GSH) / (GSH + GSO)
TPSR = (5 x 180) / (180 + 220)
TPSR = 2 hours 15 minutes from your point of origin (2.25)

### Distance to Point of Safe Return (DPSR)

To calculate DISTANCE to the point of safe return you need:

1. time to point of safe return (TPSR)