Aircraft tailstrike avoidance system

US6422517B1 · kind B1 · utility

Assignee

• The Boeing Company · US

Inventors

• Wendi M. DeWitt · Everett, US
• David P. Eggold · Everett, US
• Monte R. Evans · Federal Way, US
• Mithra M. K. V. Sankrithi · Edmonds, US
• Stephen L. Wells · Bothell, US

Key dates

• Filing date: Mar 7, 2000
• Grant date: Jul 23, 2002
• Expiry date: Mar 7, 2020

Classification

• Technology area (CPC G): Physics
• CPC primary: G05D1/0653
• WIPO field: Control
• WIPO sector: Instruments

Abstract

An improvement to an aircraft flight control system is provided for reducing the likelihood of an aircraft tailstrike. The flight control system includes a pitch command provided to a pitch control device for altering the aircraft's pitch attitude. The improvement is a system of altering the pitch command to avoid an aircraft tailstrike. The improvement includes determining a current tailskid closure rate and a current tail height; comparing the current tailskid closure rate with a threshold closure rate to determine an excess closure rate amount; and adding an incremental nose-down pitch command with the pitch command to avoid a potential aircraft tailstrike. The threshold closure rate is dependent upon the current tailskid height. The incremental nose-down pitch command is calculated as a function of the excess closure rate amount. An alternative embodiment is provided in which the current height is compared with a threshold height (that is a function of the current tailskid closure rate) to determine an excess height amount. The excess height is then used to form an incremental nose-down pitch command. Another embodiment is described using both height and rate thresholds to calc…