E Evaluation of displayed Omega/VLF navigation parameters on interfaced flight deck instruments such as HSI, CDI, etc.
to the Omega/VLF installation including high-power electrical loads and E Assessment of all switching and transfer functions pertaining electrical bus switching.
G Evaluation to determine whether there exists any electromagnetic or radio frequency interference between the Omega/VLF installation and other onboard equipment, or vice versa.
H Evaluation of the acessibility of all controls pertaining to the Omega/VLF installation.
I Evaluation of the visibility of the displays and annunciators pertaining to the Omega/VLF installation during day and night lighting conditions. No distracting cockpit glare or refections may be introduced.
J Analysis of crew workload when operating the Omega/VLF equipment.
K Evaluation of diurnal effects on the performance of the Omega/VLE system.
(ii) Determination of Navigation Error Flight Test. The initial certification of each Omega/VLF system to be used for IFR operations should be based on a demonstration of system accuracy by recording the Omega/VLF equipment position and comparing it to the actual position of at least 100 locations distributed throughout the Omega/VLE operational area. These measures should be recorded in flight by overflight of a known ground reference point at low altitude (less than 3,000' above ground level (AGL)) or comparison with a good multiple DME fix. The data should demonstrate that the appropriate accuracy criteria of paragraph 9 are met on a 95 percent probability basis. Flights into known poor signal areas should be conducted to verify that the caution indications for bad geometry and poor signal quality function properly. A ground or flight test for P-static protection, if appropriate, should be conducted. Normal flight manuevers should not cause loss of the Omega/VLF signal and the system dynamic response should be confirmed. Any unusual flight technical errors or errors resulting from use of the autopilot and flight director should be evaluated and examined. At least 50 percent of the accuracy measurements should be accomplished in areas of marginal performance. The system should demonstrate its ability to re-acquire the Omega/VLF signal after power interruption and in areas of marginal performance.
b. Follow-On Airworthiness Installation Approvals. This type of approval refers to installation approvals in any model or type of aircraft after a first-time airworthiness approval of the particular Omega/VLF equipment has been issued. Follow-on approvals may use the first-time airworthiness approval, which was either a IC or an STC, as a basis for installation approval.
Follow-on installation approvals may be accomplished by TC or SIC, or may be in the form of a field approval on an FAA Form 337. The applicant or installing agency requesting a follow-on Omega/VLF installation utilizing this method of data approval should:
Par. 10 13
(1) Contact either the manufacturer or organization responsible for obtaining the first-time airworthiness approval in order to:
(i) Obtain a sample airplane flight manual (AFM) or rotorcraft flight manual (REM) supplement (or supplemental flight manual, as appropriate).
(ii) Obtain verification of the equipment approval status, including the model of the antenna and software program identification.
(iii) Discuss any problem areas and seek assistance in their solution.
(2) Conduct a similar data evaluation as outlined in paragraph 10a(2).
(3) Conduct flight evaluations similar to the flight tests outlined in paragraph 10a(3) (1).
(4) Verify that the ohmic bonding check of the aircraft has been conducted and that appropriate numbers and types of static dischargers are installed if an E-Field antenna is used, or that a skin map has determined the appropriate location for the antenna if an H-Field antenna is used.
(5) Verify that the maximum expected groundspeed of the aircraft is less than the maximun operating speed for which the Omega/VIF equipment is qualified.
(6) Spot-check en route navigation accuracy and verify proper system operation by conducting an evaluation flight. The flight test should be of sufficient length and should follow a plan which permits proper functional evaluation of the Omega/VIF systen installation. Accuracy should be verified by conducting at least two low-level overflights of known landmarks (i.e., a VOR station). (A DME-DE position fix may be substituted for one of the low-level overflights.) During this flight, the most significant (to the navigation solution) Omega and VLE communication stations (one Omega and one VLE station) should be deselected approximately 50 percent of the time. The purpose of this test flight is not to validate navigation error values, but rather to verify that in the course of this installation nothing was done to compromise the accuracy of the system as determined by the first-time approval. Errors in excess of the values listed in paragraph 9 should be evaluated to determine possible causes. If a logical explanation is not available, additional flight test data points should be collected in the area(s) where the excessive error occurred. If such error (s) persists, approval of the installation should be withheld.
11. OPERATIONAL CONSIDERATIONS.
Operation in the NAS. The aircraft should have navigational equipment installed and operating appropriate to the ground facilities to be used (not including Omega/VLF systems). Within the conterminous United States, this requirement may be met with the installation of a VOR receiver in addition to the Omega/VLF system approved for IFR operation.
14 Par. 10
b. Operational Area. Operators and their flightcrews should consult the approved flight manual supplement for their aircraft to determine approved operational areas that may apply to their aircraft. Flightcrews must be aware that operational areas may be different for different Omega/VIF systems, and the appropriate operating area(s) for a particular system can only be determined by reference to the approved flight manual or other FAA approved documents.
Thomas E. McSweeny Acting Deputy Director, Aircraft Certification Service Par. 11 15