AeroData Drift Down Integration

By integrating your AeroData account with the PPS Flight Planning System (PPS), you can easily cover appropriate drift down procedures for your flight and improve your decision-making accordingly.

Once the integration has been setup, the calculation of appropriate drift down procedures becomes a part of the logical workflow in PPS. The dispatcher simply selects drift down and depressurization criteria and then specifies the adequate airports – all based on your engine airframe combination on your AeroData account.

How it works

The system will attempt to calculate based on the limitations of Method I. In case the calculated result is less than the allowable MTOW required for Method 1, Method 2 will be applicable. The calculated data including geographic points, which define the enroute performance profile, is sent back to PPS. Notice that the enroute performance system accounts for the use, as required, of engine and wing anti-ice and applicable MEL items.

If an airport, which is normally considered as a possible enroute alternate, is unavailable for some reason (NAVAID outage or weather), the dispatcher may remove it from the adequate airports list and add another suitable adequate airport to be considered during system calculation. The final depressurization and terrain analyses are automatically added to the flight log for review before final upload to CrewBriefing.

Method 1

Method 1 requires the aircraft to take off at a weight which ensures that if an engine failure occurs anywhere from V1 to the destination, the aircraft’s net altitude capability will clear all obstructions 5 SM either side of the intended route by 1,000 feet until reaching the destination.

The aircraft must also have a positive net gradient at 1,500 feet above the destination airport. Under optimum conditions, these requirements provide actual aircraft altitude capability of approximately 6,000 feet over the most critical obstruction and 6,500 feet above the destination field elevation when operating at enroute climb speed and planned conditions.

Method 1 analysis provides a Maximum Enroute Take-off Weight (M1METW) that is based on the forecast winds and temperatures aloft, bleed configuration, and ice protection configuration. M1METW is the maximum allowable weight at which the aircraft can take off and still comply with Method 1 requirements

Method 2

Method 2 (drift down) requires that if an engine failure occurs, the aircraft must be able to divert to at least one suitable airport from normal cruise altitude and the aircraft’s net drift down altitude will clear all obstructions 5 SM either side of the route of flight by 2,000 feet until reaching the diversion airport.

The aircraft must also have a positive net gradient at 1,500 feet above the diversion airport. Under optimum conditions, these requirements provide actual aircraft altitude capability of approximately 7,000 feet over the most critical obstruction and 6,500 feet above the destination field elevation when operating at optimum drift down speed and planned conditions.

Method 2 analysis provides a Maximum Enroute Take-off Weight (M2METW) that is based on the forecast winds and temperatures aloft, bleed configuration, and ice protection configuration. M2METW is the maximum allowable weight at which the aircraft can take off while still complying with Method 2 requirements. Additionally, Method 2 analysis provides a list of drift down-suitable airports for one or more segments along the route of flight. Each segment is defined by start- and end-points referenced from either the origin airport, the destination airport or navaids along the route of flight.

Method 2 analysis assumes that the aircraft diverts directly to the suitable airport from any point along the planned route and that the suitable airport is no more than 300 NM from the abeam point of the route. If the suitable airport is the destination airport, it is assumed that the aircraft will continue along the flight plan route. It is also assumed that, if the aircraft arrives at the suitable airport geographically before the drift down maneuver is completed, the aircraft will complete the drift down maneuver over the suitable airport in order to reduce aircraft weight by fuel burn-off. The drift down maneuver is considered complete when the aircraft reaches level-off altitude.

In accordance with regulations, Method 2 analysis begins at cruise altitude. Because an engine failure may occur before reaching normal cruise altitude, the aircraft must be able to return to land to the departure airport or divert to a suitable take-off alternate in the event of an engine failure before reaching cruise altitude. Therefore, if a take-off alternate is required, PPS determines an M1METW to ensure adequate terrain clearance to the take-off alternate. The lesser of the METW for the filed route or the METW for the take-off alternate is then used by PPS to determine MTOW.