EDTO from Scratch: A Learning Path
Extended Diversion Time Operations (EDTO) is how aeroplanes fly far from airports where they could land. Follow these steps in order, from the basic idea to planning a route with live tools.
Step by step
- EDTO Explained: Extended Diversion Time Operations from Scratch: what EDTO is, why it exists, threshold time and maximum diversion time
- Adequate vs Suitable Aerodrome: What Is the Difference?: which airports can be used, and when
- EDTO Approval and Dispatch Requirements Explained: approval levels and the checks before every flight
- How to Calculate an Equal Time Point (ETP): the formula for where to divert, with an example
- Equal time point calculator: try the formula with your own numbers
- EDTO flight planner: circles, route validation, ETPs and live weather on a map
- Polar Routes Explained: What Is Special About Flying Near the Poles: what is special about flying near the poles
- Polar Operations Requirements Checklist (FAA): what the FAA requires for polar operations
What a diversion circle looks like
A diversion circle is drawn around an alternate airport. Its radius is the one-engine-inoperative speed multiplied by the diversion time. The table shows the radius for three example speeds. Your aircraft's approved speed is what counts, and it is not the same for every type.
| Diversion time | At 350 kt | At 400 kt | At 450 kt |
|---|---|---|---|
| 60 min | 350 NM | 400 NM | 450 NM |
| 90 min | 525 NM | 600 NM | 675 NM |
| 120 min | 700 NM | 800 NM | 900 NM |
| 138 min | 805 NM | 920 NM | 1035 NM |
| 180 min | 1050 NM | 1200 NM | 1350 NM |
| 207 min | 1208 NM | 1380 NM | 1553 NM |
| 240 min | 1400 NM | 1600 NM | 1800 NM |
Still air, for illustration only. Approved diversion times such as 120 and 180 minutes, and the 15 percent extensions (138 and 207), come from the operator's approval.
Key terms
- Threshold time: the range to an en-route alternate, set by the State, beyond which an EDTO approval is needed.
- Maximum diversion time: the longest diversion time the operator's approval allows.
- Adequate aerodrome: can handle the aeroplane. Suitable aerodrome: adequate, with weather and runway conditions good enough at the time of use.
- Equal time point (ETP): where continuing and returning take the same time.
- EDTO-significant system: a system whose time limit can restrict how far the flight may go, for example cargo fire suppression.
FAQ
Is EDTO only for twin-engine aeroplanes?
It applies to turbine-engine aeroplanes with two or more engines, though the thresholds differ. The older term ETOPS covered twins.
Can I use these tools for real planning?
No. They are training tools. Use your approved data, your operator's procedures and your State's rules.