Question: If the marker beacons in my airplane are inoperative, can I legally accept a Category I ILS approach from air traffic control?

Answer: That depends. You'll want to ensure you've complied with 14 CFR 91.213 for flying with inoperative instruments and equipment. As stated in 14 CFR 91.175(k), certain navigation aids like a VOR, NDB, or DME, if authorized in the standard instrument approach procedure for the ILS, may be substituted for the outer marker. A compass locator or precision radar could also be substituted for the outer marker as well as the middle marker. Therefore, if the ILS approach you wish to fly has another means of identifying the markers and the airplane you're flying has that equipment installed and operative, you would be able to legally accept the approach. For additional information on the components of an ILS, visit AOPA Online. To learn more on using GPS in lieu of DME or an ADF, see AOPA's Air Traffic Services Brief.