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Wing Tip Clearance Hazard
From SKYbrary Wiki
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| Category: | Ground Operations | 
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| Content source: | SKYbrary | 
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| Content control: | EUROCONTROL | 
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Description
Taxiways are designated for use by all or only some aircraft types. Provided that errors of ATC Taxy Clearance, or the compliance of aircraft flight crew with clearances or standard routings, are not made, the primary risk of wing tip collision is present in aircraft holding or collective manoeuvring areas such as those often found approaching departure runway entry points. Large Aircraft where the wing tip may not be visible to the pilots, may be invited to manoeuvre, sometimes at night, so as to vary the queuing order. Such movement will often need to be carried out without taxiway centrelines to follow. The responsibility for aircraft safety when taxying remains wholly that of each aircraft commander and sometimes, the potential hazard of wingtip collision are known to an airport operator and their liability is then mitigated by ATIS or NOTAM statements such as “wingtip clearance is not assured”.
Examples of the way in which wing tip collision has occurred can be found in the reports on the three serious incidents listed under Further Reading below.
All the aircraft involved in these occurrences were, like most modern transport aircraft, swept wing types which are subject to a phenomenon known as ‘swept wing growth’ or ‘wing creep’. This occurs during a turn when the wing tip describes an arc greater than the normal wingspan due to the geometry of the aircraft and the arrangement of the landing gear. It is one of the reasons for the manufacturer’s cautions usually found in the Flight Crew Training Manuals. Although the effect is less noticeable at moderate curvature of turn, it still serves to erode the perceived wing tip clearance in any turn.