In order to obtain the operating permit in the high-intensity radiation field environment, the civil aircraft must carry out the protection design and airworthiness verification in accordance with the airworthiness provisions related to the protection of high-intensity radiation field (HIRF) issued by airworthiness authorities. Currently, the internal HIRF environment of aircraft is determined mainly through test methods and similarity assessment method. In this paper, for the first time, the data estimation method is used to determine the internal environment level of HIRF for the 23 part aircraft with only class a display system, so as to realize the airworthiness verification of HIRF protection for the whole aircraft. The key technology and feasibility of this method are discussed, which provides reference for the protection verification of civil aircraft HIRF. The method proposed in this paper has been applied to the practical engineering of Y12F aircraft HIRF protection airworthiness verification, which effectively reduces the complexity of the whole machine protection airworthiness verification. The method saves the test cost and improves the test efficiency.