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High/Low Energy Ground Impacts – RFFS Procedures
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|Category:||Emergency & Contingency|
This article describes the differences between low and high impact crashes in respect to RFFS procedures.
Low impact crashes
- General information:
- No severe damage or fuselage break-up;
- High percentage of survivors;
- Considerations and specifics in RFFS procedures:
- RFFS personnel should consider the possibility of fuel fires despite the aircraft being relatively intact
- Occupants are likely to be able to extricate themselves and leave the aircraft on their own
- Regardless of the above, it is possible that people are trapped and/or severely injured and are unable to move
- RFFS personnel should initiate extrication procedures only after donning full protective clothing and self-contained breathing apparatus
- Handline teams should back up rescue personnel for protection from a flash fire.
Two typical examples of low impact crashes are belly landings and ditches.
A belly landing (also known as wheels-up landing) is a planned event in which the flight crew makes a controlled emergency landing on the ground. This situation is usually caused by a gear or hydraulic failure. Considerations and specifics in RFFS procedures:
- Scraping along the ground may cause rupture of fuel lines and tanks, therefore application of 'foam carpet' before landing should be considered
- Friction generates large amounts of heat and may produce sparks
- Occurrence of fires is not uncommon but also not inevitable
- Suppression efforts to minimize ignition are extremely urgent
- RFFS personnel should consider the fact that it is almost impossible to maintain control of the aircraft and it may veer off the runway. Also, the place where the aircraft comes to rest is uncertain
- RFFS apparatus should be staged safely away from the aircraft to avoid being hit
- The aircraft should be pursued after it has passed staged vehicles
- In case a fire occurs, an aggressive attack to keep the fire from the fuselage (especially at the exits) is critical for the safe evacuation of survivors.
Ditching is a planned event in which the flight crew knowingly makes a controlled emergency landing in water. The crew usually has enough time to plan their actions and to alert the rescue agencies. Considerations and specifics in RFFS procedures:
- Injuries are usually minor
- Saving occupants from drowning may be a significant challenge for RFFS personnel
- If properly organized, rescue vessels and personnel, trained in water rescue are very effective in such cases
- Fire is unlikely to occur.
High Impact Crashes
- General information:
- Severe damage or fuselage break-up
- Reduced likelihood of occupant survival
Considerations and specifics in RFFS procedures depend on the crash scenario. Some notable examples are:
- Wide-bodied aircraft
- These aircraft are sturdier than the others thus increasing the chances of survival. Therefore, every large piece of the wreckage needs to be carefully checked.
- Strategic and tactical problems in rescue and fire operations are compounded by the large size of the aircraft and high number of occupants.
- Hillside crashes
- The aircraft is likely to break apart.
- The aircraft may cartwheel and, as a result, the main structural components may be torn off and scattered over a wide area.
- Occupants may be thrown from the aircraft before it comes to rest. Therefore a thorough and wide-ranging search should be carried out for casualties.
- Aircraft fires may be difficult to reach thus limiting firefighting for preventing the fire from spreading.
- Fuel may flow downhill quickly or be scattered over a large area thus increasing the challenges for the firefighters as the fire may spread unexpectedly fast.
- Crashes involving structures
- Generally, a crash into a building creates a more complex situation than a crash into the ground or water.
- Structural damage to the building might occur that could cause it to collapse.
- A thorough search and evacuation of the buildings should be done. This task becomes more complicated due to the unknown number of people in the buildings.
- Sightseers should be kept as far away from the area as possible.
- Rescue personnel should prohibit smoking and take precautions to eliminate other sources of ignition.
- Fuel leaks are very likely to occur thus further complicating the situation e.g. by contaminating the waterways. Efforts should be made to minimize such events and to notify the respective authorities.
- Fires may be widely separated and may spread rapidly because of scattered fuel, severed gas lines, damage to electrical systems, etc.
- Water crashes
- Fire extinguishing and rescue operations may be extremely challenging as fuel can spread over the water.
- If practical, a blanket of foam may be applied to the area where the fuel is spread.
- RFFS personnel should consider the possibility of fuel rising to the surface and coming in contact with the engines that are still hot which can cause a fire.
- RFFS personnel should be aware of the possibility that aircraft wreckage may be floating because of air trapped inside. In such cases, opening a hole above the water level could let the air free and cause the wreckage to submerge before the rescue is complete. Therefore such wreckages are best approached below the water level.
- Depending on factors such as age and physical condition, hypothermia may prove lethal in a matter of minutes. Therefore, specialized equipment (e.g. flotation suits, wet suits, etc.) are required for rescue operations in cold weather.
- Air boats are the best alternative for aircraft accidents in swamps, marshes and tidal flats when neither boats nor most vehicles can be used.
- Rescue and Fire Fighting Services
- RFFS Apparatus and Equipment
- Post Crash Fires
- Emergency Evacuation on Land
- Emergency Evacuation on Water
- Ditching: Fixed Wing Aircraft
- Ditching: Rotary Wing Aircraft
- FRS Operational Guidance: Aircraft Incidents, CFR UK.
- Smoke, fire and fumes in transport aircraft, past history, current risks and recommended mitigations, Royal Aeronautical Society, UK.