FAA Office of Aerospace Medicine
Civil Aerospace Medical Institute

Report No: DOT/FAA/AM-18/09

Title and Subtitle: Antihistamines and Fatal Aircraft Mishaps in Instrument Meteorological Conditions

Report Date: July 2018

Authors: Gildea KM, Hileman CR, Rogers P, Salazar GJ, Paskoff LN

Abstract:
Background: Research indicates that first-generation antihistamine usage may impair pilot performance by increasing the likelihood of vestibular illusions, spatial disorientation, and/or cognitive impairment. Second- and third-generation antihistamines generally have fewer impairing side effects and are approved for pilot use. We hypothesized that toxicological findings positive for second- and third-generation antihistamines are less likely to be associated with pilots involved in fatal mishaps than first-generation antihistamines.

Methods: The evaluated population consisted of 1,475 US civil pilots fatally injured between September 30, 2008 and October 01, 2014. Mishap factors evaluated included year, weather conditions, airman rating, recent airman flight time, quarter of year, and time of day. Due to the low prevalence of positive antihistamine findings a count-based model was selected, which can account for rare outcomes.

Results: The means and variances were close for both regression models supporting the assumption that the data follow a Poisson distribution; first-generation antihistamine mishap airmen (N = 582, M = 0.17, S2 = 0.17) with second- and third-generation antihistamine mishap airmen (N = 116, M = 0.20, S2 = 0.18). The data indicate fewer airmen with second- and third-generation antihistamines than first-generation antihistamines in their system are fatally injured while flying in IMC conditions.

Discussion: Whether the lower incidence is a factor of greater usage of first-generation antihistamines versus second- and third-generation antihistamines by the pilot population or fewer deleterious side effects with second- and third-generation antihistamines is unclear. These results engender cautious optimism but additional research is necessary to determine why these differences exist.

Key Words: Loss of Control, controlled flight into terrain, spatial disorientation, visual illusions, antihistamines

No. of Pages: 14