Attacking Ramp Damage - Some Possible Approaches

Air Safety Week, Oct 6, 2003

Training videos. Produced by the carrier or by the Federal Aviation Administration, for required viewing during annual recurrent training. Video to present case histories for students' overnight viewing, with a question and answer page to be filled out at the end of each object lesson in the educational video so supervisors can ensure that employees have actually viewed the video.

Sample case study: Mary was a last-chance baggage handler whose job was to rush late boarding passenger luggage to aircraft with jet engines inhaling or propellers turning. One night she simply forgot that 'the only safe way from aft to forward of the airplane (and vice versa) was around the wingtip.' This is what happened because of a hectic schedule and a moment's inattention (photo of worker laid out on ramp, possibly followed by morgue-slab shot for emphasis).

Wing tip aids. Add tip lights oriented to shine ahead for obstacle illumination in ramp areas (colored navigation lights are to be seen, not to 'see with'). The lights would shine outwards slightly to avoid blinding marshallers.

Incorporate a wing-tip proximity sensor that sounds a distinctive aural alarm in the cockpit and at the same time switches on the strobe light mounted in the wing tip - once the Doppler effect crosses a pre-set alarm threshold. Very attention-getting. Not that expensive an 'add on' in the context of savings to airline image, professional pride, loss of airframe utilization, schedule disruption, insurance premiums and the like.

Closed circuit television (CCTV). A proximity sensor alerting system would be further enhanced by CCTV cameras mounted at each wingtip and one in the tail.

Tail warning sensors. Another application for non-contact proximity sensors. Such tail-mounted sensors might help prevent tip-to-tail crunches. As soon as the approaching airplane's wing tip Doppler signal was high, the

strobe light in the 'crunchee' aircraft would be triggered (its passive proximity receptor and lights being wired into the battery bus for the inanimate, unpowered and unlit airplane's case). In addition, the threatened aircraft's logo-lights would cook off, instantly illuminating the threatened aircraft's empennage and vertical fin.

For pushback protection, that same tail-warning system's active Doppler could be armed by the wheels rolling backwards - which also would cause the tail-strobe to pulse, and the system would aurally warn (via the tug-driver and pilot intercom) of any obstacles to the rear of which the tug-driver might be unaware.

The 'Drop-Chock' concept. Many tug-powered pushback accidents occur from loss of traction on icy, greasy, sloping or rain-slippery ramps. Appropriately treaded tires, ballasted tugs and a 'drop chock' tug emergency brake might help avoid those slithering drifts into the embarrassing limelight of a ramp accident. The drop-chock emergency brake would consist of a flat-bottomed, spike-studded, hard rubber wedge stowed above each wheel that would quickly drop into place in front of each tire. Each tug tire would ride up its drop-chock's incline, jamming to a halt against the drop-chock's upper extremity - while the tug's weight and momentum would drive the chock's spike-studs into the tarmac. Because of the drop-chock's ground-grabbing feature, the tug and airplane won't continue any out-of-control slide on slippery or snowy ramps - and would also avoid the nosewheel damage attendant to any tug-airplane jack-knifing. A manufacturer might dub the feature DropChox.

Proximity Sensor Technologies

Proximity sensors can be of the contact or non-contact type. Contact sensors usually feature a microswitch activated by a whisker, roller, lever, reed-switch or the like. Non-contact proximity sensors can use either ultrasonics (beyond the range of human hearing), Doppler microwave radar or infrared optical. Optics are most commonly employed for close-range non-contact sensing - usually an LED [light emitting diode] and a photo diode. When the object comes into place, light is reflected down a short tube within the sensor body onto the photo diode, causing a signal to be sent to the next part of the circuit.

Proximity sensors are commonplace components in robotics (and in home and vehicle security systems to detect approach, interference and theft.

See www.iasa.com.au/prox.htm

[Copyright 2003 PBI Media, LLC. All rights reserved.]