document: U.S. Air Force war planes participating in Operation Desert Shield are flying again after they were ordered grounded for 24 hours following a rash of crashes . Pentagon and Air Force officials said regular training flight schedules resumed Thursday at noon local time -LRB- 5 a.m. EDT -RRB- . The flights account for a majority of U.S. air missions in the Persian Gulf region . The Air Force `` has not changed anything '' in flight operations as a result of the suspension of flights , Capt. A.C. Roper , a spokesman for U.S. Central Command , said in Saudi Arabia . He said Air Force officials wanted to `` examine potential hazards and to be sure they were doing everything possible to prevent accidents . `` They have not identified any common cause or common contributing factors '' to the recent accidents , he added . At the Pentagon , spokesman Pete Williams said the number of U.S. aircraft accidents in the gulf - including three separate crashes this week - were not out of the ordinary . However , suspension of training flights indicated otherwise . Williams said the Air Force gave its pilots in the gulf `` safety awareness '' briefings during the flight ban in order `` to review what they need to do to fly more safely . '' Aircraft on operational missions were not grounded , said Col. Miguel Monteverde , another Pentagon spokesman . Those included reconnaissance aircraft , refueling tanker planes and F-15 jets patrolling areas near the Kuwait or Iraqi borders . He said pilots of those planes received special safety briefings but their flight schedules were not changed . `` So there was no degradation of our ability to defend ourselves , '' Monteverde said . Desert Shield , the largest U.S. military buildup since the Vietnam War , involves an estimated 700 Air Force combat and support aircraft . Williams said information about the number of flight hours in Desert Shield is classified and will not be disclosed . As a result , he said , he could not compare the accident rate with that of previous deployments . The toll for accidental deaths since Operation Desert Shield began rose to 31 on Wednesday when an Air Force F-111 fighter-bomber crashed on a training mission in Saudi Arabia , killing both crew members . On Monday , two pilots were killed in the crash of an Air Force F-4 Phantom reconnaissance jet in Saudi Arabia , and just hours earlier two Marine Corps UH-1 Huey helicopters , each carrying four crew members , crashed over the Arabian Sea , killing all eight men . Williams said the Air Force was the only service that has taken special measures to review safety in the gulf since this week 's accidents . `` They 're concerned about the accidents , they 're concerned about the number of accidents that happened so quickly over a short period of time , '' he told reporters . He said , however , that the military 's safety record in Desert Shield remained good . `` Given the amount of flying that has to be done , given the extraordinary circumstances and given the higher than ordinary operating tempo in the area , I think our service people are doing very well , but any accident is cause for concern , '' he said . Five U.S. aircraft have been involved in fatal crashes in the gulf area since the start of Desert Shield two months ago : an F-111 , an F-4 Phantom reconnaissance jet , an F-15E and two Marine Corps UH-1 Huey helicopters . Also , a C-5 transport plane crashed in West Germany while ferrying equipment to Saudi Arabia . Also , 20 other aircraft have been involved in non-fatal accidents in the gulf area , Williams said . Fifteen of those were helicopters .
extractive_keyphrases: fatal crashes operation desert shield regular training flight
abstractive_keyphrases: u.s. air force war planes u.s. aircraft accidents u.s. air missions