Low Visibility Taxi

AIM ¶ 4-3-19 Low Visibility Taxi

AIM 4-3-19 explains low visibility taxi procedures, LVOSMGCS, RVR thresholds, and pilot responsibilities. Study guide for checkride and written test prep.

In Plain English

In low visibility, the tower controller may not be able to see your aircraft on the airport surface, which means they can't visually verify you're following taxi instructions. This makes pilot communication and situational awareness critical.

Key points from this paragraph:

  • Notify ATC immediately if you encounter difficulties, become disoriented, or have vision problems (such as taxiing toward the sun).
  • Focus entirely on taxiing — defer checklists and non-essential radio chatter until the aircraft is stopped with brakes set.
  • AC 120-57 (LVOSMGCS) — "Low Visibility Operations Surface Movement Guidance and Control System," pronounced "LVO SMIGS" — provides a model low visibility taxi plan for airports with operations below 1,200 feet RVR.

LVOSMGCS plans address two levels:

  • Operations less than 1,200 feet RVR down to 500 feet RVR
  • Operations less than 500 feet RVR

These plans may add extra lighting, markings, and procedures for both aircrews and vehicle operators. This is a recommended practice intended to prevent runway incursions and surface collisions when controllers lose visual reference to the movement area.

AIM Source Text
FAA AIM ¶ 4-3-19
4-3-19. 4-3-19. Taxi During Low Visibility Pilots and aircraft operators should be constantly aware that during certain low visibility conditions the movement of aircraft and vehicles on airports may not be visible to the tower controller. This may prevent visual confirmation of an aircraft's adherence to taxi instructions. Of vital importance is the need for pilots to notify the controller when difficulties are encountered or at the first indication of becoming disoriented. Pilots should proceed with extreme caution when taxiing toward the sun. When vision difficulties are encountered pilots should immediately inform the controller. Advisory Circular 120-57, Low Visibility Operations Surface Movement Guidance and Control System, commonly known as LVOSMGCS (pronounced “LVO SMIGS”) describes an adequate example of a low visibility taxi plan for any airport which has takeoff or landing operations in less than 1,200 feet runway visual range (RVR) visibility conditions. These plans, which affect aircrew and vehicle operators, may incorporate additional lighting, markings, and procedures to control airport surface traffic. They will be addressed at two levels; operations less than 1,200 feet RVR to 500 feet RVR and operations less than 500 feet RVR. NOTE- Specific lighting systems and surface markings may be found in paragraph 2-1-10 , Taxiway Lights, and paragraph 2-3-4 , Taxiway Markings. When low visibility conditions exist, pilots should focus their entire attention on the safe operation of the aircraft while it is moving. Checklists and nonessential communication should be withheld until the aircraft is stopped and the brakes set.
Oral Exam Questions a DPE Might Ask
Q1Why is pilot vigilance especially important when taxiing in low visibility?
Per AIM 4-3-19, in certain low visibility conditions the tower controller may not be able to see aircraft or vehicles on the airport, so they cannot visually confirm an aircraft is complying with taxi instructions. Pilots must notify the controller immediately if they encounter difficulties or become disoriented.
Q2What is LVOSMGCS and when does it apply?
Per AIM 4-3-19, LVOSMGCS (pronounced "LVO SMIGS") stands for Low Visibility Operations Surface Movement Guidance and Control System, described in AC 120-57. It provides an example low visibility taxi plan for airports with takeoff or landing operations in less than 1,200 feet RVR, addressed at two levels: less than 1,200 feet RVR to 500 feet RVR, and less than 500 feet RVR.
Q3What should pilots do regarding checklists and communication while taxiing in low visibility?
Per AIM 4-3-19, when low visibility conditions exist, pilots should focus their entire attention on the safe operation of the aircraft while it is moving. Checklists and nonessential communication should be withheld until the aircraft is stopped and the brakes are set.
Related Paragraphs in AIM Chapter 4
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AIM 4-3-19 — Taxi During Low Visibility