DECISION POINTS
 

1️⃣ Point of No-Return Distance (PNR-D)
2️⃣ Point of No-Return Time (PNR-T)
3️⃣ Equitime Point Distance (ETP-D)
4️⃣ Equitime Point Time (ETP-T)
5️⃣ How to plot all points on the E6-B

 

🛠 Considering a route from A to B

• D distance from A to B: 500nm
• T flight time, taking ground speed into account: 3h 50min
• A endurance WITHOUT reserve: 4h
• R range WITHOUT reserve, considering ground speed (4 × 130): 520nm
• TAS true airspeed: 140kt
• VsA ground speed outbound, accounting for wind: VsA=130kt
• VsR ground speed return: VsR=150kt
• VsA+Vsr equal 2 times the true airspeed : VsA + VsR = 2 x TAS
   

1️⃣ Point of No-Return Distance (PNR-D

The Point of No-Return Distance (PNR-D) is the location on a flight route beyond which an aircraft can no longer return to the departure airport with the remaining fuel. It is calculated based on distance, speed, and fuel consumption.

Master formula:

​A (VsA x VsR) / (VsA + VsR) ⇒ 4 x (130 x 150) / (130 + 150) ⇒ 278nm
 

Simplified formula:

(R x VsR) / 2TAS ⇒ (520 x 150) / 280 ⇒ 278nm
 

💡Usage:

• Allows planning the point at which it becomes necessary to continue to the destination or return.
• Important for safety and fuel management on long-haul flights.
   

2️⃣ Point of No-Return Time (PNR-T)

The Point of No-Return Time (PNR-T) is the Point of No-Return Distance, but expressed in terms of time.
 

Master formula:

A (VsR / (VsA + VsR)) ⇒ (4 x 150) / (130 + 150)) ⇒ 02h 08min
 

Simplified formula:

(A x Vsr) / 2TAS ⇒ (4x150) / 280 ⇒ 02h 08min
 

3️⃣ Equitime Point Distance (ETP-D)

The Equitime Point Distance (PET-D) is the location where the time to continue to the destination equals the time to return to the departure airport or to an alternate airport. It is used to plan safe diversions.
 

Master formula:

D (VsR / (VsA + VsR)) ⇒ (500 x 150) / (130 + 150) ⇒ 268nm

Simplified formula:

(D x Vsr) / 2TAS ⇒ (500x150) / 280 ⇒ 268nm

💡Usage:

• Allows determining the point at which it is faster to return than to continue.
• Essential for planning transoceanic flights or operations in remote areas.
   

4️⃣ Equitime Point Time (ETP-T)

The Equitime Point Time (ETP-T) is the Equitime Point Distance, but expressed in terms of time.
 

Master formula:

D (VsR / (VsA + VsR)) ⇒ (500 x 150) / (130 x 280)) ⇒ 02h 04min

Simplified formula:

(T x Vsr) / 2TAS ⇒ (3.8 x150) / 280 ⇒ 02h 04min

 

5️⃣ How to plot all points on the E6-B

Beyond the complicated formulas, there is a simple and quick method to obtain all four pieces of information simultaneously, without doing any calculations. You just need to use an E6-B: practical, battery-free, and it never fails. So much so that a watch, a compass, and an E6-B are enough to navigate around the world. This very handy instrument allows you to perform all kinds of navigation calculations.
 

• Align 2 x TAS (280) on VsR (150)
   
• Opposite R (520) you read PNR-D (278)
• Opposite A (4) you read PNR-T (128 ie:02h08)
• Opposite D (500) you read ETP-D (268)
• Opposite T (3:50) you read ETP-T (124 ie:02h04)