Commercial Pilot ACS Study Guide: Communication, Light Signals, and Runway Lighting Systems

Clear communication and a strong understanding of airport lighting are essential to safe airport operations. Under Area of Operation III: Airport and Seaplane Base Operations, the Commercial Pilot ACS expects applicants to demonstrate knowledge of proper radio procedures, ATC light gun signals, and airport and runway lighting systems.

At Angel Aviation, commercial students are expected to communicate professionally, understand the visual information presented around an airport, and know how to respond when normal communication is unavailable.

Effective Radio Communication

Commercial pilots should use clear, concise, and standardized radio phraseology. Before transmitting, listen to the frequency, organize what you need to say, and avoid unnecessary communication.

A typical initial call should include:

  • Facility or station being called
  • Aircraft identification
  • Aircraft position, when applicable
  • Request or intentions
  • Relevant information requested by ATC

Pilots should understand when and how to communicate with ATIS/AWOS/ASOS, Clearance Delivery, Ground Control, Tower, Approach, and Departure, as applicable to the operation.

Always listen carefully to ATC instructions and read back safety-critical information as required. If a clearance or instruction is unclear, ask for clarification rather than making an assumption.

Lost Communications

A radio failure does not eliminate the pilot’s responsibility to safely operate the aircraft.

If communication is lost, first troubleshoot the problem as workload permits. Consider:

  • Correct frequency selected
  • Volume and squelch settings
  • Headset and microphone connections
  • Audio panel configuration
  • Circuit breakers in accordance with appropriate procedures
  • Alternate radio or communication equipment, if available

At a towered airport, pilots should be prepared to use visual light gun signals from the control tower.

ATC Light Gun Signals

Pilots should know the meaning of ATC light gun signals both on the ground and in flight.

Light Signal Aircraft on the Ground Aircraft in Flight
Steady Green Cleared for takeoff Cleared to land
Flashing Green Cleared to taxi Return for landing
Steady Red Stop Give way to other aircraft and continue circling
Flashing Red Taxi clear of runway in use Airport unsafe—do not land
Flashing White Return to starting point on airport Not applicable
Alternating Red and Green Exercise extreme caution Exercise extreme caution

Do not simply memorize the colors. Be able to explain when these signals might be used and how you would respond safely.

Runway Lighting Systems

Runway lighting provides pilots with important information regarding runway location, alignment, remaining runway, and approach guidance, particularly during nighttime and reduced-visibility operations.

Commercial pilot applicants should be familiar with common lighting systems, including:

Runway Edge Lights
Define the edges of the runway. Runway edge lighting is generally white, with yellow replacing white on the last portion of certain instrument runways to provide a caution zone.

Runway Centerline Lights (RCLS)
Centerline lights are white until the final 3,000 feet of runway. They then alternate red and white until the final 1,000 feet, where they become red.

Touchdown Zone Lights (TDZL)
White lights arranged in rows on either side of the runway centerline identify the touchdown zone.

Runway End Identifier Lights (REIL)
Synchronized flashing white lights positioned near the runway threshold help pilots rapidly identify the approach end of a runway.

Threshold and Runway-End Lighting

Runway thresholds and ends are identified using specific colors.

  • Green lights identify the runway threshold when viewed from the approach direction.
  • Red lights identify the runway end when viewed from the runway.

Understanding lighting colors and orientation becomes especially important when operating at unfamiliar airports or at night.

Approach Lighting Systems

Approach lighting systems help pilots transition from instrument references to the runway environment and provide visual guidance during an approach.

Depending on the airport and runway, pilots may encounter systems such as:

  • ALSF – Approach Lighting System with Sequenced Flashing Lights: A high-intensity approach lighting system that provides visual guidance and runway alignment information during instrument approaches. Common variations include ALSF-1 and ALSF-2.
  • MALSR – Medium Intensity Approach Lighting System with Runway Alignment Indicator Lights: Uses medium-intensity approach lights and sequenced flashing lights to help pilots identify and align with the runway.
  • MALSF – Medium Intensity Approach Lighting System with Sequenced Flashers: A medium-intensity system that incorporates sequenced flashing lights to assist pilots in identifying the runway environment during an approach.
  • ODALS – Omnidirectional Approach Lighting System: A simpler approach lighting system using flashing lights to help pilots identify the runway approach end and establish visual alignment.

Commercial pilots should understand the general purpose of approach lighting and know how to determine which system is installed for a particular runway using current airport and chart information.

Visual Glidepath Indicators

PAPI – Precision Approach Path Indicator

A PAPI typically uses four lights to provide visual glidepath information:

  • 4 white: Too high
  • 3 white / 1 red: Slightly high
  • 2 white / 2 red: On glidepath
  • 1 white / 3 red: Slightly low
  • 4 red: Too low

VASI – Visual Approach Slope Indicator

A common VASI interpretation is:

  • White over white: High
  • Red over white: On glidepath
  • Red over red: Low

Remember: “Red over white, you’re alright.”

These systems provide visual glidepath guidance but do not replace proper aircraft control, stabilized approach criteria, or obstacle awareness.

Pilot-Controlled Lighting

At some airports, pilots can activate or adjust airport lighting using the aircraft radio on the designated frequency.

Depending on the system, 3, 5, or 7 microphone clicks within five seconds may provide different lighting intensity levels. Pilots should verify the applicable frequency and airport lighting information before relying on pilot-controlled lighting.

Risk Management

The ACS requires applicants to recognize and manage risks associated with airport communication and lighting, including:

  • Misunderstood or incomplete ATC instructions
  • Frequency congestion
  • Radio failure
  • Similar aircraft call signs
  • Distractions during critical operations
  • Misidentification of runways or taxiways
  • Reduced visibility and nighttime operations
  • Failure to recognize airport lighting configurations
  • Runway incursions or wrong-runway operations

Strong communication requires both transmitting clearly and listening carefully. When conditions become uncertain, slow the operation down and verify before proceeding.

Commercial Pilot Standard

For the practical test, be prepared to demonstrate and explain:

  • Proper aviation radio phraseology
  • Appropriate communication with ATC and other aircraft
  • Recognition and response to ATC light gun signals
  • Procedures following communication failure
  • Runway, threshold, and airport lighting
  • PAPI and VASI indications
  • Pilot-controlled lighting
  • Effective situational awareness during airport operations

A commercial pilot should be comfortable operating in both towered and non-towered environments and should have a plan for maintaining safe operations if normal communication becomes unavailable.

Study Questions

Before your checkride, make sure you can answer:

  1. What information should be included in an initial radio call?
  2. What should you do if you do not understand an ATC instruction?
  3. What steps would you take following a radio failure?
  4. What does a steady green light gun signal mean on the ground? In flight?
  5. What does a flashing red signal mean?
  6. How do runway centerline lights change as you approach the end of the runway?
  7. What is the purpose of REIL?
  8. How do you interpret PAPI and VASI indications?
  9. How does pilot-controlled lighting operate?
  10. Where can you determine which lighting systems are available at an airport?

 

Communication and Situational Awareness

Professional communication is not about talking quickly or sounding polished on the radio. It is about exchanging the correct information clearly, understanding instructions, and maintaining situational awareness throughout the operation.

Combined with a strong understanding of runway and airport lighting systems, these skills allow commercial pilots to operate confidently and safely in changing airport environments.

Communicate clearly, verify what you see and hear, and never allow uncertainty to become an assumption.

FAA References

Review the current Commercial Pilot – Airplane Airman Certification Standards (FAA-S-ACS-7) along with applicable FAA resources:

  • FAA Aeronautical Information Manual (AIM)
  • FAA Pilot’s Handbook of Aeronautical Knowledge
  • FAA Chart Supplement
  • FAA airport diagrams and aeronautical charts