5.  Failure to parallel the desired radial on a track  interception problem. Without this step, orientation  to the desired radial can be confusing. Since pilots  think in terms of left and right of course, aligning the  aircraft position to the radial/course is essential. 6.  Overshooting and undershooting radials on  interception problems. 7.  Overcontrolling corrections during tracking, especially  close to the station. 8.  Misinterpretation of station passage. On VOR  receivers not equipped with an ON/OFF flag, a  voice transmission on the combined communication  and navigation radio (NAV/COM) in use for VOR  may cause the same TO/FROM fluctuations on the  ambiguity meter as shown during station passage.  Read the whole receiver—TO/FROM, CDI, and  OBS—before you make a decision. Do not utilize a  VOR reading observed while transmitting. 9.  Chasing the CDI, resulting in homing instead of  tracking. Careless heading control and failure to  bracket wind corrections make this error common. 1.  VOR test facility (VOT) or a radiated test signal from  an appropriately rated radio repair station. 2.  Certified checkpoints on the airport surface. 3.  Certified airborne checkpoints. checks, and an appropriate endorsement, within 30 days prior  to flight under IFR. To comply with this requirement and to  ensure satisfactory operation of the airborne system, use the  following means for checking VOR receiver accuracy: The Federal Aviation Administration (FAA) VOT transmits  a test signal that provides users a convenient means to  determine the operational status and accuracy of a VOR  receiver while on the ground where a VOT is located.  Locations of VOTs are published in the A/FD. Two  means of identification are used: one is a series of dots  and the other is a continuous tone. Information concerning  an individual test signal can be obtained from the local  flight service station (FSS.) The airborne use of VOT is  permitted; however, its use is strictly limited to those areas/ altitudes specifically authorized in the A/FD or appropriate  supplement. To use the VOT service, tune in the VOT frequency 108.0  MHz on the VOR receiver. With the CDI centered, the  OBS should read 0° with the TO/FROM indication showing  FROM or the OBS should read 180° with the TO/FROM  indication showing TO. Should the VOR receiver operate an  RMI, it would indicate 180° on any OBS setting. A radiated VOT from an appropriately rated radio repair  station serves the same purpose as an FAA VOT signal, and  the check is made in much the same manner as a VOT with  some differences. The frequency normally approved by the Federal  Communications Commission (FCC) is 108.0 MHz;  however, repair stations are not permitted to radiate the  VOR test signal continuously. The owner or operator of the  aircraft must make arrangements with the repair station to  have the test signal transmitted. A representative of the repair  station must make an entry into the aircraft logbook or other  permanent record certifying to the radial accuracy and the  date of transmission. Airborne and ground checkpoints consist of certified radials  that should be received at specific points on the airport surface  or over specific landmarks while airborne in the immediate  vicinity of the airport. Locations of these checkpoints are  published in the A/FD. The effectiveness of the VOR depends upon proper use and  adjustment of both ground and airborne equipment. The accuracy of course alignment of the VOR is generally  plus or minus 1°. On some VORs, minor course roughness  may be observed, evidenced by course needle or brief flag  alarm. At a few stations, usually in mountainous terrain,  the pilot may occasionally observe a brief course needle  oscillation similar to the indication of “approaching station.”  Pilots flying over unfamiliar routes are cautioned to be on  the alert for these vagaries, and in particular, to use the TO/ FROM indicator to determine positive station passage. Certain propeller revolutions per minute (rpm) settings or  helicopter rotor speeds can cause the VOR CDI to fluctuate  as much as plus or minus 6°. Slight changes to the RPM  setting normally smooths out this roughness. Pilots are urged  to check for this modulation phenomenon prior to reporting  a VOR station or aircraft equipment for unsatisfactory  operation. VOR system course sensitivity may be checked by noting  the number of degrees of change as the OBS is rotated to  move the CDI from center to the last dot on either side. The  course selected should not exceed 10° or 12° either side. In  addition, Title 14 of the Code of Federal Regulations (14  CFR) part 91 provides for certain VOR equipment accuracy  VOR Test Facility (VOT) VOR Accuracy Certified Checkpoints VOR Receiver Accuracy Check 9-16