What happened
On 13 May 1997, an advertising blimp became detached from its mooring at a construction site near the Red Cow Hotel on the Naas Road, Dublin. The aircraft, which was being used for promotional purposes, had been moored to a temporary single-story building. At approximately 13:58 UTC, a security guard observed the craft drifting at an altitude between 300 and 500 feet. The blimp was moving toward Dublin City and in the general direction of Dublin Airport, trailing a 100-foot nylon cable. Despite alerts to airport police and Air Traffic Control, the aircraft was not recovered and was presumed to have drifted toward the sea.
The investigation
The investigation focused on why the mooring failed and the regulatory compliance of the operation. Investigators examined the mooring site and found that the nylon line, chain, and padlock were all missing, suggesting that the detachment was not a mechanical failure but the result of unauthorised interference. The investigation also reviewed the operator's compliance with Irish Aviation Authority (IAA) regulations. While the operator had previously notified the IAA regarding aerial photography activities, they had not submitted the required seven-day notice for this specific moored operation, which was required because the site was within five miles of an aerodrome.
Findings
- The blimp became detached due to human interference at the mooring site.
- The safety device, intended to deflate the blimp at 3,000 feet, did not meet the requirement for rapid deflation, as the craft could have drifted for a long period before the device activated.
- The operation failed to comply with IAA notification requirements regarding proximity to an aerodrome.
- The drifting craft posed a high risk to low-level helicopter operations and likely crossed the approach path for Dublin Airport's Runway 28, potentially while obscured by cloud cover.
- The use of a lightweight, easily cut nylon line facilitated the unauthorized release of the craft.