I made this in my notes after reading about driftdown in the asa book.
Methods for complying with driftdown regs
****Applies to A/C certified AFTER 8/29/1959****
Dispatch A/C with a weight that will
****Applies to A/C certified AFTER 9/30/1958
Dispatch A/C with a weight that will
Driftdown requirments for 2 engine out enroute
***Applicable to aircraft with MORE than 2 engines AND certified AFTER 8/29/1959***
To meet this requirement, the A/C must NEVER:
Anyone have a way to make it simple? I know the basics of what driftdown does but the regs are hard to make sense of.
Methods for complying with driftdown regs
****Applies to A/C certified AFTER 8/29/1959****
Dispatch A/C with a weight that will
- Allow it to climb
- Allow it to clear all obs within 5 SM either side by 1000 feet vertically
- Allow it to climb when it reaches its diversion airport at 1,500 feet
****Applies to A/C certified AFTER 9/30/1958
Dispatch A/C with a weight that will
- NOT PROHIBIT a net flight path that:
- Clears all obs within 5 SM either side BY 2,000 FEET
- Allow it to climb when it reaches its diversion airport at 1,500 feet
- Clears all obs within 5 SM either side BY 2,000 FEET
- Engine failure occurs at most critical route point
- A/C will pass a critical obs and will be equal distance or closer to a NAVAID than the CO (critical obs)
- MOST ADVERSE winds are used for planning
- Fuel dumping will occur if applicable
- Legal enroute alternate is specified
- Fuel+oil consumed can be considered when determining flight path
- All this means is that you get credit for the plane losing weight while it descends
Driftdown requirments for 2 engine out enroute
***Applicable to aircraft with MORE than 2 engines AND certified AFTER 8/29/1959***
To meet this requirement, the A/C must NEVER:
- Be > 90 minutes from a compliant 121.197 airport
- A .197 airport has a runway long enough that the aircraft WILL STOP WITHIN (60% for turboJETS and 70% for turboPROPS) of the runway length when it arrives
- Exceed a weight that prevents it from maintaining a net flight path to clear the highest obs 5 SM either side BY 2,000 FEET
- LOOSE BOTH ENGINES at the MOST CRITICAL flight point
- Have a positive climb at 1,500 feet above the alternate airport
- Have enough fuel to fly at this altitude/location AT LEAST 15 minutes
- Conduct fuel dumping if applicable and consumptions can be considered
Thus for simplicity, method one is easiest to calculate and use. Unfortunately, in some parts of the world, this simpler method might prohibit certain routes, so the more complex method might have to be utilized to take advantage of the more gradual driftdown that aircraft actually make in such an emergency.
Ison, David C.. Aircraft Dispatcher Oral Exam Guide (Kindle): Prepare for the FAA Oral and Practical Exam to Earn Your Aircraft Dispatcher Certificate (Oral Exam Guide Series) (Kindle Locations 927-929). Aviation Supplies and Academics, Inc.. Kindle Edition.
Anyone have a way to make it simple? I know the basics of what driftdown does but the regs are hard to make sense of.