From NASA’s Aviation Safety Reporting System – a pilot report

In this report from the NASA Aviation Reporting System, an instructor and student received a powerful reminder of the dangers of carburetor ice. Carburetor ice occurs due to the effect of fuel vaporization and the decrease in air pressure which causes a sharp temperature drop in the carburetor. If water vapor in the air condenses when the carburetor temperature is at or below freezing, ice may form on internal surfaces of the carburetor, including the throttle valve. Carburetor ice is most likely to occur in high humidity conditions at temperatures below 70 degrees (F). Ed.

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My student and I decided to go out and practice VFR landings…before low ceilings arrived later that evening. The temperature was around 40 degrees F and the dew point spread about 4 degrees C [7.2 degrees F]. We taxied out to [Runway] XXL and flew two right VFR patterns, each landing on [Runway] XXR. I flew the first pattern to demonstrate, and the student flew the second pattern. As we came in on final for the second pattern, the engine RPM dropped, and the propeller came to a stop at the end of the ground roll of the second landing. We quickly used the momentum to exit XXR onto Runway XY and hold short of XXL. I stated to Tower that my engine just quit, and the Tower Controller confirmed observing this over the Tower frequency. My student and I were immediately able to get the engine started on Runway XY to taxi back to the ramp.

In hindsight, I realize what likely occurred, but it is speculation. As my student performed the run-up before I took off of XXL, I recall noticing a 200 RPM drop when the student tested the carburetor heat. Having flown a fuel injected C172 a couple times before this flight, I was not in the habit of turning the carb heat on.… I did forget to turn the carb heat on during my first pattern and mentioned this out loud to the student while on final for XXR during my demonstration. The student took the controls for the second pattern while on upwind for XXR. During the student’s pattern, our downwind was extended for landing traffic, and he also forgot to turn the carb heat on as he configured for landing. I noticed this, but with this flight being a pre-solo evaluation, I decided to make a note of this for later and did not correct it immediately. While on final for his landing, he pulled the throttle to idle for the entirety of final approach. As we continued the ground roll after his landing, the prop stopped turning about halfway down the runway. I do not recall hearing the engine quit, just that the RPM began to get pretty low. With the weather conditions, I strongly suspect carb icing. The engine didn’t have time to warm up, either, after two patterns in these conditions. To prevent further occurrence, I will be more diligent when switching between aircraft with different systems and identify differences before beginning a flight. I also need to emphasize the landing checklist while on downwind for myself and my students. I…am fully aware of the consequences of not turning on the carb heat in conditions where carb icing is prevalent.

The secret is out…it is sunny and warm in south Florida. And there are a lot of people from the north who would prefer the south Florida weather in the middle of winter for a dose of vitamin D. This winter reality means busy airports, busy airspace, and long security lines. In other words, pack your patience and some extra fuel.

So was the case on a recent flight from Cincinnati (KLUK) to the Fort Lauderdale – Hollywood International Airport (KFLL). FAA-mandated ground stops are not uncommon this time of year due to capacity issues even with mitigation strategies in place such as making use of military airspace and other restricted to accommodate a higher volume of traffic. Aircraft must be appropriately metered into Florida so that the system is not overwhelmed – everything from ATC staffing to physical space in the air and on the ground. Introduce some weather into the equation and things get even tighter. “Controlled chaos” is the phrase that comes to mind.

An RNAV (GPS) arrival is a guarantee into south Florida to ensure an orderly flow of traffic and separate the southbound arriving traffic from the northbound departing traffic. Our common route of flight from Cincinnati takes us through a departure gate used by Cincinnati approach control, KENLN, located on the BLUEGRASS departure from the Cincinnati Norther Kentucky International Airport (KCVG), and then south over Lexington, Knoxville, Atlanta, and then the published Standard Terminal Arrival Procedure (STAR) in southern Georgia at the ZPLEN intersection for the TEEKY arrival into KFLL.

Those responsible for the naming of arrival fixes are certainly clever and funny and often use local themes and landmarks to name fixes. Take, for example, the FRISBE departure from KFLL that has you pass over two initial fixes, LLBOW “Elbo,” and ROOOM “Room” paying homage to the famous Elbo Room in Ft. Lauderdale Beach founded in 1938. Well done! But I digress.

The fist thing you’ll notice for our TEEKY arrival into KFLL is the amount of information to consume on the chart itself. In fact, the FAA version is two pages. In this case, I prefer the Jeppesen equivalent chart as all of the information is located on a single page. In the iPad era, with the ability to pinch and zoom, it doesn’t really matter how small the print might be.

FAA TEEKY arrival

Jeppesen equivalent TEEKY arrival

Evident by the altitudes and speeds noted on the procedure, the TEEKY is reserved for turbojet aircraft. This restriction is also stated in the notes section of the arrival, along with a notice to pilots to expect a “descend via” clearance as part of the arrival.

Descend Via – An abbreviated ATC clearance that requires compliance with a published procedure’s lateral path and associated speed restrictions and provides a pilot-discretion descent to comply with published altitude restrictions until descending to the “Bottom Altitude” published on the STAR

Given the amount of crossing restrictions, vertical navigation is a must on this procedure. The Collins Pro Line 21 suite makes this relatively simple by setting the bottom altitude of the procedure – 6,000’ landing west – and selecting vertical navigation, “VNAV,” on the controller. It’s up to the pilot to control the speed with the throttle, but the navigation computers will do the rest. In an aircraft equipped with auto throttles, the pilots only need to watch the automation do its thing.

On the TEEKY, we must cross FIGNA at or below FL310 (31,000’), JASBO at or above FL260 and at 280kts. DANNA must be crossed between FL230 and FL260, TEEKY at or above 12,000’, and BANTY between 10,000’ and 11,000’ at 250kts and HEEZE at 7,000′. Given we are landing runway 28L at KFLL (west), we’ll continue to GOYLE at a mandatory 7,000’, and finally, FAMBA, at a mandatory 6,000’. You can see how busy this could get if you didn’t have the advantage of vertical navigation.

We were in a conga line of about eight aircraft flying the same procedure to the same destination. This was mix of airline traffic and business aviation traffic with a variety of capabilities, but the arrival procedure equalizes everyone by the same arrival path, mandatory altitudes and speeds. Beyond the mandatory speed of 250kts at BANTY, given the close proximity of aircraft, we were further given multiple speed restrictions by ATC. “Slow to 230 kts,” slow to 210 kts,” “slow to 170 kts and maintain 170 kts to the final approach fix on the ILS for Runway 28R.”

Yes, as you can imagine there’s a lot of radio traffic and the importance of clear, concise radio communication and precise execution of the instructions is paramount and what makes the system work safely. The local approach facilities will assume pilots have the appropriate procedures, frequencies and information at the ready to respond to multiple requests quickly. It’s also expected that pilots will fly precise altitudes and speeds when required (remember that when your CFI is strict about maintaining 85 kts. on downwind, 75 kts. on base and 65 kts. on final (or whatever your training aircraft calls for.))

After landing, it is also necessary to have awareness of the taxiway layout and likely path to the FBO as the instructions will come just as quickly as the speed restrictions in flight. After our hurried taxi instructions, we were parked on the ramp and the passengers on their way for a cold weather reprieve.