Overview
Following a review of accidents involving commercial jets during take-off and landing, aviation authorities in the early 1990s identified the need to update existing regulations and flight manuals. The European Joint Aviation Authorities (JAA) released one Directive addressing this issue. However, there have been concerns that the Joint Airworthiness Requirements (JAR) do not adequately take into consideration the specific performance of smaller commuter or business aircraft.
CONTAMRUNWAY aimed to support the JAA in reviewing the validity of the existing requirements for operation on runways contaminated by rain, snow and ice for small and commuter aircraft. Because of the scope of the subject, this study was limited to the determination of the contaminated runway drag and the aquaplaning speed of free rolling wheels.
The main objectives of CONTAMRUNWAY were to:
- identify the most important parameters related to runway drag;
- assess deviations from the AMJ 25x1591 Directive 'Supplementary performance information for take-off from wet runways and for operation on runways contaminated by standing water, slush, loose snow, compacted snow or ice';
- establish the basis for calculating theoretical drag on contaminated runways and to determine the aquaplaning speed of free rolling wheels, by tests conducted in water ponds;
- highlight to relevant authorities the areas where current regulations need modification.
Funding
Results
CONTAMRUNWAY has
- reviewed existing regulations and manuals relating to aircraft certification with respect to runway conditions;
- conducted water pond trials, in order to simulate runway contamination, with two aircraft models, a Cessna Citation II business jet and a larger Dassault Falcon 2000 business jet, assumed to represent a wide range of executive and commuter aircraft;
- performed complementary tarmac tests on dry snow using the above aircraft plus a Saab 2000 turboprop regional aircraft, focusing on the measurement of hydrodynamic drag and aquaplaning phenomena;
- carried out a theoretical study on the effect of water-induced drag corresponding to e.g. airframe and wheel size, and proposed a computer-based forecast methodology for spray impingement drag in order to increase the safety of smaller aircraft during take-off and landing;
- concluded that the mentioned AMJ 25x1591 Directive is in general not applicable for smaller aircraft with respect to certification and operation;
- communicated the results to the JAA Flight Study Group and other world-wide authorities, in order to pave the way for changes in existing regulations.
Policy implications
CONTAMRUNWAY has been limited to smaller business and commuter aircraft, which indicates the need to enlarge the database to allow for a comprehensive assessment of operational regulations, such as JAR-OPS1. Airworthiness authorities should promote more advanced computation models that would allow for the calculation of aircraft-specific values for the so-called balanced field length, as recommended in existing operational regulations.