On Sep 5th 2018 Mexico’s DGAC reported in a press conference first results into the investigation. There were three flight crew on the flight deck, a first officer in training was pilot flying in the right hand seat. The takeoff run began in a head wind scenario, which quickly changed into a strong right crosswind and ultimately a strong tail wind as result of a microburst. The investigation so far has not found any technical (both engines were operating normally until being separated from the wing) or human factors issue contributing to the accident. With the flight data, confirmed by meteorologists, simulator tests were conducted, no flight crew was able to get through the scenario with a different outcome. However, the training of the first officer under training had not been authorized and was not carried out according to the required protocols. Although this is not the cause of the accident, it will cause administrative response by the DGAC to establish the responsibilities and apply according sanctions.
On Sep 6th 2018 the DGAC also released the preliminary technical report in Spanish releasing some FDR graphics as well as surveillance camera photos showing the weather development, otherwise the text of the report mainly engages in introducing the commission, its sub groups and who did what but no narrative of the accident sequence whatsoever, except that the report specifically mentions the presense of a microburst over the aerodrome.
The simulation graphics suggest, the aircraft became airborne at a right crosswind of about 11 knots and was in the initial climb, when the right crosswind intensified to 33 knots and turned into a tailwind of 24 knots causing the aircraft to lose height again.
The FDR graphs reports that the speed over ground was steadily increasing initially with some head wind component (thus showing the IAS higher than speed over ground) which turned into a tail wind about 5 seconds prior to end of recording, the aircraft reached a maximum IAS of about 151 KIAS decreasing again to about 125 KIAS at the end of the recording. The aircraft reached a maximum height of about 30 feet AGL.
In the description of one of the photos the DGAC mentions that there were impact marks of the left hand engine on taxiway B.