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Cover Story

Avoiding Ground Mishaps: What Every Operator Needs to Know

While many aviation safety efforts correctly focus on the critical phases of flight, preventing ground incidents is equally vital. Just as in flight, there’s little room for error. Even dents and dings can set an operator back tens of thousands of dollars in repairs and lost income.

Hangar and ground movements rank among the top aviation safety concerns, according to Eric Barfield of Hope Aviation Insurance. “We all read about the smoking hole in the ground, but fender benders don’t get the attention,” said the South Carolina insurer, who also serves on NBAA’s Safety Committee. “Insurance pays millions per year” for damage that occurs on the ground.

The causes vary as much as the accidents, but, as in flight, human factors are everything. Barfield offered some examples. A tug operator became complacent moving a small jet into a cavernous hangar, thinking ‘Why do I need a wing walker?’ The transition from the bright sunshine outdoors into the dark shadows of the hangar ended with the sickening sound of metal scraping metal as the jet was pushed over a tug parked in back of the hangar.

How about a puncture of the aircraft’s pressure vessel? That seemingly small accident cost a hapless owner $477,000 in repairs and seven months of lost revenue from an idle Cessna Citation. “Not to mention the headaches of paperwork and constantly working the issue,” said Barfield.

The causes vary as much as the accidents, but, as in flight, human factors are everything.

NBAA’s Safety Committee estimates that careless ground operations cost the general aviation industry more than $100 million per year. By far the biggest risk involves towing, followed by ramp, service equipment and hangar movements.

Ground Vehicle Safety Pointers

At first glance, tug safety might seem to be a likely cause of the losses, but a careful driver can perform the checks in less than a minute. Just like a pilot doing a preflight, operators should walk around the tug to ensure there’s nothing broken, missing or out-of-place. Check the limitations placard. Is this the right tug for the job? Check the tires for damage and proper inflation. Inspect the battery for corrosion, and ensure the cell caps are in place. Is there enough oil or coolant? Check the locking pins and safety pins.

Safety begins as you approach any ramp vehicle. Be aware of your surroundings. Check clearances, the proximity of other aircraft, equipment and workers. Check for foreign object debris (FOD) on your vehicle, remove any trash and secure loose items – anything that could be blown away by wind or jet blast.

For tractors without tow bars, ensure the emergency disconnect switch isn’t blocked, and check the bank support plate, safety clip and straps. For any tug, check the brakes before you move, and ensure the brake pedal doesn’t go all the way to the floor.

After starting the engine, listen for unusual sounds and check the instrument readings. Is the power steering working? Is there excessive play in the wheel? Any safety equipment required by the Occupational Safety & Health Administration (OSHA), such as seat belts, lights and horn, must be working. If you discover any problems with those items, OSHA requires you to tag it so the vehicle won’t be used until it’s fixed.

NBAA’s Safety Committee estimates that careless ground operations cost the general aviation industry more than $100 million per year. By far, the biggest risk involves towing, followed by ramp, service equipment and hangar movements.

The pace of driving a tug or tractor should be limited to walking speed in congested areas, and slow down if you suspect fluids or ice are on the ramp. Keep your legs and feet inside the vehicle, and only move with a passenger in the seat, not holding onto the side of the vehicle. Never place objects or cargo on the vehicle’s surface.

If there’s any doubt about clearance or space, or if you ever lose sight of the wing walker: stop.

Lead the tow bar when driving; pushing it could cause the vehicle to jackknife. Always stop your vehicle to speak to approaching people, and never allow anyone to jump on or off while the vehicle is moving.

When approaching an aircraft, approach from the front, facing the aircraft, while maintaining a 10-foot circle-of-safety from the aircraft at all times.

Use the parking brake and turn off the engine before leaving your tug. It’s also a good practice to chock the rear wheel closest to the driver’s seat before walking away. This requires you to scan the area behind the vehicle when you return to move it. Fuel trucks also should be chocked and grounded when servicing the airplane; ground power units should be chocked and not positioned under the aircraft’s tail. Golf carts should be shut off, braked and chocked when unattended.

The NBAA Safety Committee recommends using at least two wing walkers when moving aircraft into or out of the hangar. Survey the area before moving an airplane. Where are the hidden risks? Ensure that the hangar doors are secure and can’t be moved by wind or jet blast. Don’t let wings overlap when parking aircraft in hangars because they may settle. It’s a good idea to include procedures for aircraft ground movement in both the flight and maintenance operations manual and ensure that employees understand them.

That also applies to taxiing. Pilots should scan for risks, such as ground service equipment, narrow rows of aircraft, loose chocks or slope. If there’s any doubt about the marshaller’s hand signals: stop.

When parking an aircraft, use warning cones on wing tips and tails, chock both the main and nose wheel, and remove the airstair mat before starting engines.

If all of this seems familiar, it is. “It seems to be the same old stuff,” remarked Chartis Insurance’s Ray Stanton, who refers to the continuing mishaps as “hangar rash.” Stanton, who travels the country evaluating ramp operations for insurance companies and fixed base operators, concludes that the safest operators have ample supervision, with supervisors involved on the ramp, not at meetings or in front of computers when aircraft are being moved.

“We want to see highly reflective vests, hearing protection, good lighting and well-marked parking spots,” said Stanton. “We also want to see people working at a reasonable pace, not running because they’re pressed for time.”

Tire and Passenger Safety

Simply keeping aircraft tires inflated properly can increase ground safety and save operators money, according to Keat Pruszenski of Michelin. If tires are over-inflated, less tire surface is gripping the pavement and nylon chords stretch, including the rubber. The extra tension can cause objects, such as foreign object debris, to cut into the rubber, weakening the tire. Under-inflated tires force the tread to rise to the center, causing a high rate of wear where the inner plys lack tension, which could lead to a leak or the plys unraveling.

Preventing tires from failing also means understanding how temperature affects inflation. “You’ll experience a 1 percent decrease in inflation for every 5 degrees Fahrenheit decrease,” said Pruszenski. “For a flight from Florida to Minnesota, it’s common to see a 50 degree drop in temperature and a loss of 10 percent of tire pressure.”

Passengers also are an important part of ground safety. Keep them off the ramp unless boarding or deplaning the aircraft, and ensure they receive the safety briefing as required under Parts 135 and 91. Those FARs require passengers sitting next to an emergency exit to be able to open that exit during an emergency. Mobility-impaired passengers may require an assistant during flight. Assistants need to be briefed on emergency procedures as well.

Boarding and deplaning mobility-impaired passengers can be a mutual effort among the crew and medical staff meeting the aircraft, according to Ed Boyer of Angel Flight in Virginia Beach, VA. For stretcher transfers, there should be at least two people at the head and two at the foot of the stretcher. He emphasized that unless crewmembers are medically qualified, they should not render any other assistance.

For More Information

The Hangar and Ground Safety section of NBAA’s web site has several resources in this area, including presentations from NBAA’s Safety Committee, an OSHA compliance checklist and more, at

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