None of the pitot tubes were ever recovered so investigators were unable to determine for certain what caused the blockage. Investigators believe that the most likely culprit was the black and yellow mud dauber, a type of solitary sphecid wasp well known to Dominican pilots, which tends to establish its nest in artificial, cylindrical structures, or make its own cylindrical nest out of mud. According to the final report, section 2.3 – "Aircraft maintenance factors", the aircraft had not flown in 20 days, however, this was not the duration for which pitots remained uncovered, but was evidently enough time to allow the wasps the opportunity to construct nests in the tubes. According to Cetin Birgen, president and CEO of Birgenair, the pitot covers were removed two days before the accident in order to conduct an engine test run.