5.4 Signal Checks & the Readability Scale

5.4 Signal Checks & the Readability Scale

Quick Answer: Ask for a signal (or radio) check on a frequency that won’t interfere with others. Say SIGNAL CHECK or RADIO CHECK 1, 2, 3, 4, 5. HOW DO YOU READ ME? OVER, include your call sign, and keep the test ≤10 seconds. Readability is 1 Bad through 5 Excellent. Name the test type: Signal (airborne), Preflight (before departure), or Maintenance (ground maintenance). Watson Lake example ends READING YOU STRENGTH FIVE.

RIC-21 §5.7.5 Signal (or Radio) Checks is short, numerical, and heavily tested. Candidates must know the script, the ten-second limit, the 1–5 scale wording, the three category names, and the Watson Lake example.

When and where to request a check

When your radio station requires a signal (or radio) check, follow this procedure:

1. Call another aircraft or aeronautical ground station on any appropriate frequency that will not interfere with the normal working of other aircraft or ground stations, and request a signal check.
2. The signal check consists of: “SIGNAL (or RADIO) CHECK 1, 2, 3, 4, 5. HOW DO YOU READ ME? OVER.”
3. Your station identification (call sign) should also be transmitted during such test transmissions.
4. Signal checks should not last more than 10 seconds.
5. When replying or receiving a reply, use the readability scale below.

Exam traps: long carrier “testing” monologues, checks on a congested tower frequency when a quiet practice frequency is required, and tests without a call sign (anonymous keying is wrong).

Exact check phraseology

You may say SIGNAL CHECK or RADIO CHECK—RIC-21 allows both labels. The digit string is spoken as counting one through five, then the readability question, then OVER so the other station can answer.

Conceptual full sequence:

1. Call the other station (called first, THIS IS, your call sign—as in any proper call).
2. State the request (e.g., REQUEST SIGNAL CHECK ON …).
3. Deliver the short 1–2–3–4–5 check within ten seconds.
4. Release for their readability report.

The count gives the receiving operator a sustained sample of modulation and strength—not a license to ramble. Ten seconds is a hard study-guide limit; plan the words before you press PTT.

Readability scale (memorize exact meanings)

When replying or receiving a reply to a signal check, use this scale:

Drill both directions: number → meaning and meaning → number. Common confusions:

• 2 is intermittent (“now and then”), not merely “a bit weak.”
• 3 is continuous difficulty, not silence.
• 4 is solid readable (good), not “perfect.”
• 5 is perfectly readable (excellent).

Replies in practice often sound like “reading you strength five” or “readability five,” matching the Watson Lake model below. On the exam, match the official quality words to the numbers.

Three categories of communications checks

Communications checks are categorized as follows:

Same technical 1–5 scale; different label based on when/where the test occurs. Do not call an airborne test a “preflight check,” or a hangar bench test a “signal check,” if the exam asks for the category name.

Official example — Watson Lake Radio (RIC-21)

Aircraft request:

WATSON LAKE RADIO
THIS IS
CESSNA FOXTROT ALFA BRAVO CHARLIE
REQUEST SIGNAL CHECK ON FIVE SIX EIGHT ZERO

Ground reply:

CESSNA FOXTROT ALFA BRAVO CHARLIE
THIS IS
WATSON LAKE RADIO
READING YOU STRENGTH FIVE
OVER

Points to extract:

• Full call format: Watson Lake Radio first, THIS IS, Cessna FABC.
• Clear REQUEST SIGNAL CHECK plus the frequency 5680 (spoken under number rules as five six eight zero in the guide’s style).
• Reply addresses the aircraft first, identifies Watson Lake Radio, then reports READING YOU STRENGTH FIVE (scale 5 = excellent / perfectly readable).
• Ends with OVER because a response cycle may continue or the aircraft may acknowledge.

If Watson Lake had heard only fragments, a report of strength two (poor—readable now and then) would tell the pilot the link is intermittent—change altitude, frequency, or troubleshooting posture rather than assume the radio is “fine.”

Operational judgment

• Prefer a check frequency or moment that does not step on busy ATC or another aircraft’s clearance.
• Keep the count and question inside ten seconds.
• Always identify with your call sign.
• Report the scale honestly—overstating readability hides real equipment problems.
• Use the correct category name if the examiner asks what kind of check you just performed.

Link to the rest of §5.7

Signal checks still obey calling discipline: listen first, called station first, no harmful interference, priority traffic still wins the channel. A radio check is not a reason to interrupt distress, urgency, or safety traffic. After you have readability, return to normal four-part message handling for operational traffic.

Self-test before the accredited exam

1. Recite the five readability definitions without looking.
2. Write the full SIGNAL/RADIO CHECK sentence including OVER.
3. Name the three categories and one scenario for each.
4. Reconstruct the Watson Lake / Cessna FABC dialogue.
5. State the maximum duration of a signal check (10 seconds).

Official source

RIC-21 Issue 3, §5.7.5 Signal (or Radio) Checks, including the readability scale, category definitions, and Watson Lake Radio example. ISED study guide for the ROC-A.