Exhibit 21 Subsidiaries March 1997 Aerotherm Corporation Anedyn, Inc. Anedyn Power Company AT/Mexico Holdings Inc. Audio Technical Services Inc. Cinco Investors, Ltd. Data Management Design, Inc. Dyn Funding Corporation Dyn Logistics Services Inc. Dyn Marine Services, Inc. Dyn Marine Services of Virginia, Inc. Dyn/Mexico Holdings Inc. Dyn Network Management, Inc. Dyn Pacific Aerospace Services, Inc. Dyn Realty Corporation Dyn Systems Technology, Inc. Dyn Trade Systems, Inc. DynAir Technical Services, Inc. Dynalectron Corporation Dynalectron Systems Inc. DynCIS, Inc. DynCorp Advanced Repair Technology, Inc. DynCorp Aerospace Operations, Inc. DynCorp Aerospace Operations(UK) Ltd. DynCorp Aviacion de Mexico S. A. de C. V. DynCorp Aviation Services, Inc. DynCorp Biotechnology and Health Services, Inc. DynCorp Environmental, Energy & National Security Programs, Inc. DynCorp Information & Engineering Technology, Inc. DynCorp International Services GmbH DynCorp International Services, Inc. DynCorp International Services Ltd. DynCorp Management Resources LLC DynCorp Procurement Systems, Inc. DynCorp of Colorado, Inc. DynCorp Panama, Inc. DynCorp Tri-Cities Services, Inc. DynCorp Viar Inc. DynCorp West Virginia Inc. DynEagle Inc. DynEx, Inc. DynKePRO LLC DynMcDermott Petroleum Operations Company DynSolutions, Inc. Electric Utility Construction, Inc. Fuller-Austin Insulation Company Grupo DynCorp de Mexico S.A.deC.V. Grupo DynCorp Satcom S.A. de C.V. Kwajalein Services, Inc. New Mexico Technology Group LLC OLDHD Systems, Inc. Pacific TSD Corporation Sea Mobility Inc. TAI Realty Corporation