Worldwide Aeronautical Route Planner (WARP)

WARP is an optimizing aircraft route planning engine that is deployed as the core of the Advanced Computer Flight Planner (ACFP) route planning system in operation at the U.S. Air Force’s Air Mobility Command. ACFP is used to route cargo aircraft worldwide in addition to mid-air refuelling operations.

WARP uses sophisticated search techniques to produce routes that minimize the burn of fuel while satisfying all other flight constraints. The routing process factors in the effects of weather, aircraft performance, and airspace restrictions. WARP can also determine the optimal fuel load required to accomplish a mission and/or the maximum payload that can be carried.

Worldwide Aeronautical Route Planner (WARP)
A Route Produced by WARP
The map above shows a route produced by WARP for a flight from Dover Air Force Base in the United States to Ramstein Air Base in Germany. It saves thousands of pounds of fuel when compared with other contending routes, including the shortest-distance route between the airports. WARP is believed to save the USAF tens of millions of pounds of fuel every year.

WARP lets flight planners specify a variety of parameters, including:

  • Support for aircraft-based flight performance modelling of the major military transport aircraft, and the ability to readily add civilian aircraft.
  • Ground path and altitude selection to minimize fuel burn based on weather (wind and temperature) and aircraft performance characteristics.
  • Scalable route processing architecture. Any number of routing engines can load balance the set of active route requests through a single web services and database installation.
  • Segment-based routing types include Airway, Pressure/Direct, Navaid, Great Circle, Navzone, and commercial-like selection from among a fixed set of ground paths.
  • Payload maximization.
  • Alternate, divert, and recovery planning (i.e., contingencies for POA or other airfield unavailability).
  • Top-of-climb and begin-descent calculations.
  • Equal Time Point (ETP) and depressurization calculations. ETP is a determination of the point along the primary path of flight where the time required to return to a contingency airfield is the same as diverting forward to another contingency airfield. Any number of ETP/depressurization calculations can be computed in a flight plan.
  • Automatic switching of routing type (e.g., Airway or Pressure/Direct) based on custom-definable boundaries (usually defined by over-land ​ ​vs over-water location).
  • Inflight payload changes (increase or decrease)Air refuelling for both tanker and receiver, with ability to handle optimum, maximum, or fixed fuel transfer amounts.
  • Calculation of step climb locations when they result in fuel savings.
  • Orbits and holds.
  • Routing via organized tracks (e.g., NATs).
  • Optimal SID and STAR selection.
  • Route re-winding (i.e., re-plan a route following the same (presumably filed) ground path but using newer weather forecast and/or modified payload and/or modified departure time and/or modified aircraft tail number.
  • Ability to plan based on departure time or arrival time(s) at any point(s) in a route (cost index value(s) automatically calculated to hit multiple constrained time points).
  • Ability to degrade fuel burn rates for a specific route request/tail over the entire route or specific route portions.
  • Support for full route planning (ICAO to ICAO), "retask" plans (mid-air to ICAO), "ground" plans (ICAO to mid-air), "overhead" plans (mid-air to mid-air).
  • Ability to avoid SUAS, system-defined, and user-defined spaces (polygons and circles), including specified altitude ranges.
  • Ability to "daisy chain" flight segments (with optional no refueling at intermediate airfields).
  • Cost indexing capabilities to adjust speed, fuel, and enroute time (our re-implementation of this capability has not been fully tested and deployed).

Although it must accommodate non-linearities and non-monotonicities in aircraft performance data, and in many cases optimize fuel burn while simultaneously maximizing payload carrying capacity, WARP typically solves even complicated route requests in less than 30 seconds.