Cessna 172 Best Glide Speed What Every Pilot Should Know

In the event of an engine failure, one of the most critical pieces of knowledge a Cessna 172 pilot must have is the aircraft’s best glide speed. This isn’t just a number from the POH—it’s a life-saving performance parameter that determines how far you can travel without power. Understanding and correctly applying this speed can mean the difference between a safe off-field landing and a high-risk outcome. Whether you're a student pilot or a seasoned aviator, mastering the nuances of glide performance in the Cessna 172 is essential.

What Is Best Glide Speed?

Best glide speed (V_G) is the airspeed at which an aircraft achieves the maximum lift-to-drag ratio (L/D_max). At this speed, the airplane travels the greatest horizontal distance for a given loss of altitude. It is not the speed for minimum sink rate—that would be slower and used when you want to stay aloft as long as possible, not go as far as possible.

For the Cessna 172, the published best glide speed in most models is **65 knots indicated airspeed (KIAS)** with the engine at idle and propeller in full fine pitch. However, this value assumes standard conditions: clean configuration, center of gravity within limits, and no wind. In real-world emergencies, adjustments may be necessary based on weight, wind, and configuration.

Tip: Always confirm the exact best glide speed for your specific Cessna 172 model year and variant—check the Pilot’s Operating Handbook (POH).

Why 65 KIAS? The Aerodynamics Behind the Number

The 65 KIAS figure isn't arbitrary. It results from extensive flight testing and aerodynamic analysis. At this speed, induced drag and parasite drag are balanced to produce optimal efficiency. Flying faster increases parasite drag disproportionately; flying slower increases induced drag due to higher angle of attack. Both reduce glide distance.

At 65 KIAS, a typical Cessna 172 achieves a glide ratio of approximately **9:1**—meaning it can travel 9 feet forward for every 1 foot of altitude lost. From 1,000 feet AGL, this translates to roughly **1.5 to 1.7 nautical miles** of glide range under ideal conditions.

However, real-world factors like headwinds, turbulence, pilot technique, and aircraft loading can significantly affect actual performance. For example, a 20-knot headwind can cut effective glide distance by nearly 30%.

Factors That Affect Best Glide Performance

While 65 KIAS is the baseline, several variables influence true best glide speed and distance:

• Aircraft Weight: Heavier aircraft require a slightly higher airspeed to maintain best L/D ratio. For every 100 lbs below max gross weight, reduce V_G by about 1–2 knots.
• Wind Conditions: Headwinds call for a slight increase in airspeed (add 1/3 to 1/2 of headwind component); tailwinds allow a slight reduction.
• Configuration: Gear down, flaps extended, or open windows increase drag and degrade glide performance—even partially extended flaps can reduce glide ratio by up to 25%.
• Altitude and Density Altitude: While best glide indicated airspeed remains constant, true airspeed increases with altitude, affecting groundspeed and range over terrain.

Factor	Effect on Best Glide Speed	Practical Adjustment
Increased Weight	Higher optimal speed	+1 to +3 KIAS above 2,000 lbs
Headwind	Requires more groundspeed	Add 1/3 of headwind component
Tailwind	Leverage wind assistance	Reduce by 1–2 KIAS
Gear or Flaps Extended	Significant drag increase	Retract immediately if possible
High Density Altitude	No change to IAS, but affects TAS	Maintain 65 KIAS, expect longer rollout

Step-by-Step: Executing a Proper Engine-Out Glide

If the engine quits, immediate and correct action is crucial. Follow this sequence to maximize your chances of reaching a safe landing zone:

1. Aviate First: Establish and maintain best glide speed immediately. Pitch attitude should result in 65 KIAS. Use outside references to stabilize attitude before relying on instruments.
2. Secure the Engine: Confirm fuel selector position, mixture rich, check magnetos, verify fuel pump on. If no restart, secure engine per checklist.
3. Identify Landing Site: Look for the nearest suitable field within glide range. Consider wind, terrain, obstacles, and surface type.
4. Communicate: Squawk 7700, transmit MAYDAY on frequency or guard, declare intentions.
5. Prepare for Landing: Complete memory items: fuel pump off, master off (near touchdown), doors unlatched, passengers briefed.
6. Manage Energy: Adjust speed only when necessary—e.g., add 5–10 knots when turning final or dealing with downdrafts.

“Speed control is the single most important factor in maximizing glide distance. Panic-induced over-controlling leads to poor outcomes.” — Captain David Ito, FAA Aviation Safety Inspector and former instructor

Real-World Scenario: Gliding Back to the Field

In 2018, a Cessna 172P experienced total engine failure shortly after takeoff from a rural airport in Montana. The pilot, a commercial-rated flyer with recent training, immediately pitched for 65 KIAS. Despite a 15-knot headwind, he adjusted his speed to ~68 KIAS to maintain glide efficiency. He identified a freshly harvested wheat field 1.3 NM ahead—within calculated reach.

He maintained precise airspeed, executed a forward slip to lose excess altitude on final, and landed safely with minimal damage. Post-flight analysis confirmed that had he flown just 10 knots faster, he would have fallen short by nearly 400 feet. This case underscores the importance of disciplined airspeed management during emergencies.

Tip: Practice simulated engine failures regularly. Pick a spot on the ground and try to glide to it using only best glide speed—this builds instinctive control.

Common Misconceptions About Best Glide

Several myths persist among pilots regarding best glide:

• Myth: “Flying slower will help me stay in the air longer.”
  Reality: While slower speeds increase time aloft, they reduce distance covered. Best glide optimizes distance, not duration.
• Myth: “I can glide farther if I circle to lose altitude.”
  Reality: Turning increases load factor and induced drag, reducing effective glide ratio. Minimize turns in glide scenarios.
• Myth: “The POH number works in all configurations.”
  Reality: Any deviation from clean config—like leaving flaps down—severely impacts performance.

Frequently Asked Questions

Does best glide speed change with altitude?

No. Best glide indicated airspeed remains constant regardless of altitude. However, true airspeed increases with altitude, so ground distance covered may vary slightly depending on wind and atmospheric conditions.

Should I use flaps during a glide approach?

Only in the final phase of landing. Flaps increase drag and decrease glide ratio. Use them to steepen descent path or control touchdown point—but only after you’re certain you’ll make the target.

How do I know if I’m actually achieving best glide?

Monitor vertical speed versus forward speed. At 65 KIAS in a clean 172, you should see a descent rate of approximately 700–750 feet per minute. If you’re descending faster at the same speed, drag may be present (e.g., gear down).

Checklist: Engine-Out Emergency Response

• ✅ Pitch for 65 KIAS (adjust for weight/wind)
• ✅ Confirm engine parameters (fuel, mixture, mags)
• ✅ Attempt restart if appropriate
• ✅ Secure engine if restart fails
• ✅ Identify viable landing site
• ✅ Transmit MAYDAY / squawk 7700
• ✅ Brief passengers
• ✅ Configure aircraft (gear up, flaps up until final)
• ✅ Fly stabilized approach to touchdown

Conclusion: Mastery Saves Lives

Knowing the Cessna 172’s best glide speed is not just a checkride requirement—it’s a core survival skill. Too many otherwise capable pilots lose situational advantage in engine failures because they fail to prioritize airspeed control. The difference between 65 and 75 knots may seem minor, but in an emergency, it can cost you half a mile of glide distance.

Regularly review your POH, practice engine-out scenarios during dual instruction, and internalize the feel of best glide attitude. When seconds count, hesitation or incorrect inputs can’t be recovered. But with preparation, discipline, and respect for aerodynamics, you can turn a potential disaster into a controlled outcome.

🚀 Take action today: Schedule a flight review focused on emergency procedures. Rehearse the glide—and fly it precisely. Your next flight could depend on it.