Aircraft Tie-down Removal

CAA issued this Safety Notice is to re-emphasise to pilots the need to fully complete preflight checks, and specifically to ensure that the aircraft is free from tie-down constraints before being manoeuvred.
Recent reports submitted through the Mandatory Occurrence Reporting Scheme concern aircraft being taxied, and in one case taking off, with tie-down restraints still attached. In all cases these involved rope attachments to bulky objects such as weighted tyres and concrete blocks. All of the aircraft involved were light single-engine piston, low-wing types where the wing tie-down attachment points were hidden from the cockpit. In addition to the hazard to normal controlled flight, some of the reports featured damage to the wing-flaps and superficial damage to the runway surface. It seems to have been almost impossible to detect from the control responses and power settings required to taxi that there was anything untoward, despite the same bulky objects being difficult to move by hand when unattached.

Effective Precautions

Whilst these type of tie-down incidents do occur (as do similar incidents involving the nose-gear tow-bar), they are all easily preventable and have an established procedure in the pre-flight inspection to deal with them. It is essential to ensure that the pre-flight inspection is carried out thoroughly each time rather than being curtailed due to time pressures, distraction or a reluctance to get clothes or hands dirty. In order to make an effective check the pilot must put himself/herself in a position where the item being checked can be positively verified including, in these situations, getting under the wing to check the lower surfaces, fuselage, undercarriage and tie-down points. It is clearly important to inspect directly the tie-down attachment point to see that it is clear, rather than rely on the rope, cable or anchor being clearly visible. 

However, since experience indicates that the way pre-flight checks are carried out does not always identify a tie-down still in place, owners and pilots may wish to consider additional measures. These measures include, but are not limited to:

• Regular use of a written checklist is the best way to ensure that items are not forgotten. If the checks have become so familiar that the pilot feels no need to use the list normally, the pilot should make an effort to use the list regularly to refresh his/her memory of the detail of the items. 

• Attempting to ensure that the aircraft cannot move with a tie-down attached. A substantial chock in front of a wheel which is also attached to the anchoring object may achieve this. 

• Attaching the aircraft to a ground anchor rather than a moveable object. While aircraft have been known to break the rope while taxiing forward, a rope-end is less likely to cause serious damage than a concrete block.  

• Having more than one ‘indicator’ that an item is satisfactory/not satisfactory, e.g. tags, markers, cones, etc. showing prominently when a tie-down is not attached. An ideal system of this type would have the tags/markers visible from the cockpit for final verification. If a mobile anchoring object is used, it is suggested that these, once unattached, are moved to an obvious place where they are not in the way but can be seen from the cockpit. 

• Encouraging all persons on the aerodrome to take an interest in aircraft taxiing and to raise the alert if something untoward is noticed. If available, communicate the nature of the problem via the aerodrome ATS or the notified frequency for the aerodrome if the incident happens outside of normal operating hours.  

• Dress sensibly during winter months so that you can comfortably carry out pre-flight checks (including removing all ice) without feeling the need to curtail them due to cold and inclement weather or saturated ground. If you hire an aircraft, don’t only rely on the daily ‘A’ check or the previous pilot having carried out a full pre-flight inspection.

 

 

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