Aviation Topic of the Week
By Michael Oxner, March 14, 2004


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This week's topic:
IFR Flight Example, Part 7: Destination

In the previous part of the Example Flight, our pilots were vectored to the localizer for the ILS 24 at CYHZ. They were cleared for the straight-in ILS RWY 24 approach, and were switched to the tower. This is where we begin this week's topic: Calling in to the tower on final.

Initial Contact with Tower
    Braking Action Reports
Final Approach & Landing
    Landing Clearance
    Runway Environment
Exiting the Runway
    ASDE
    Clearing the Runway
Taxiing to Parking

Initial Contact with Tower

FART: "Halifax Tower, good afternoon, KingAir Foxtrot Alpha Romeo Tango with you seven miles final for runway two four on the ILS."
CYHZ TWR: "KingAir Foxtrot Romeo Alpha Tango, Halifax Tower, runway two four, winds two four zero at fifteen gusting twenty five, altimeter two niner four one. A DC9 just landed and reported braking action fair."
FART: "Two niner four one, copy remarks. We're over Bluenose NDB on final now."
CYHZ TWR: "Alpha Romeo Tango, roger, you're number two to a Navajo two miles final."
FART: "Alpha Romeo Tango."
Runway, wind, altimeter and sequencing instructions are issued on initial contact. In the case of IFR conditions, such as this flight, there are none since Halifax Terminal did the sequencing already. Also, as in the example above, other information deemed important is added as required.

With a runway that is less than bare and dry, pilots are often curious about runway friction. Since the ATIS in last week's example did not include a CRFI report, detailed in another topic, the pilots have little way of knowing how slippery the runway really is. The fact that there was a significant portion of the runway reported as bare and dry means that a CRFI report may be meaningless, since it may very well report values that provide a snapshot of braking action that is better than it really is. Hence, another form of pilot report can be used, and that was mentioned in the TWR's transmission above, the braking action report.

These reports are simply a description of the apparent effect on deceleration the brakes appear to have. As a result, the reports are highly subjective. The pilot's opinion of the conditions is based on his experiences with the aircraft and how he perceived the current landing, as well as the aircraft type. The aircraft type is much more important, since different aircraft behave differently. For example, a BAe-146 does not have thrust reversers, and only has brakes to slow down. An aircraft with thrust reversers may very well report a better braking action than a 146, despite the fact that the reversers were of great assistance on shortening the landing roll. Conversely, a braking report from a "heavy" aircraft may mean little to a light aircraft and vice versa. With a long runway, some aircraft may rely totally on flattened pitch (AKA discing) of propeller blades to provide deceleration and may not even use brakes. This is often the case with the Dash 8's that fly around the maritimes in eastern Canada and elsewhere. Still, pilots routinely provide ATC with braking action reports and they are relayed willingly, since this may be the best, most current form of runway report a pilot can have.

The reports are issued with a plain language description, normally including the terms "good", "fair", "poor" and "nil". They're pretty straight forward, and easily understood. A braking action report may include a little more description, such as "good for the first half, then poor on the last half."

Final Approach & Landing

As the pilots overfly the Bluenose NDB, the final approach fix for the ILS 24, they notice the glideslope needle has slowly moved down the ILS gauge and is now in the center, indicating they are on the glidepath. It is now time to begin descent. They check the altimeter with the setting just issued by TWR and confirm they are at the correct altitude for the final approach fix. A check of the groundspeed shows our pilots they are grounding, conveniently, 120 knots. Using an outdated chart to get my information, we'll use the glideslope angle of 2.7° for our example. Remember to use current, real world charts for real world flight. This slope translates to approximately 300 feet per nautical mile (actually 286 ft/nm), and since our pilots are grounding 120, that should work out to about (286x2=572) or somewhere around a 600 foot per minute descent rate. The co-pilot lowers the gear and the flaps at the command of the captain and monitors the outside environment, looking for visual contact with the approach lights and the runway environment. The captain, on the other side of the cockpit, flies the plane and monitors the gauges to ensure they stay on the localizer and glideslope (as much as the turbulence they are encountering allows, anyway), and works the throttles as required.

Eventually, the radio comes to life again, this time with the words providing a pilot permission to touchdown:

CYHZ TWR: "Alpha Romeo Tango cleared to land runway two four. Winds two four zero at fifteen gusting to twenty."
FART: "Cleared to land two four, Alpha Romeo Tango."

As the approach progresses, the captain notices the altimeter reading and notes that they are approaching decision height. This is the height at which the pilots must have established visual contact with the runway environment or execute a missed approach. The visual references required to allow a pilot to continue to a safe landing are outlined in the AIP, RAC 9.19.3. The pilots must see at least one of the following to continue below the decision height:
Not all runways will have all of the above indications. VASIS and PAPIs are often not installed on runways with glideslopes, and runways with Category II ILS and better are the only ones likely to have TDZ and centerline lights.

Inside the cockpit, the captain is drawing his breath to say, "minimums", indicating to the co-pilot that he has to call the runway in sight now or they have to go around. Just then, the co-pilot says, "I have the runway". The captain asks, "Land?", asking the co-pilot to confirm the aircraft is in a good position to continue to a landing and that the runway, at least as far as they can see, is suitable for landing. The co-pilot says, "Affirmative, I have control," clearly stating to the captain that he will continue the approach from here and that the captain can release the controls. This isn't necessarily the procedure followed in every cockpit, but our pilots have chosen to fly this way in low IFR weather.

The landing is conducted carefully in the choppy air, and the props are put to reverse pitch to slow the aircraft. Light braking is used as well to help slow the aircraft, though it isn't really necessary considering the runway is 8,800 feet long -- plenty for a Beech 200.

Exiting the Runway

When the aircraft is slowed down to a good taxi speed, the props are taken out of reverse and the pilots begin to look for a taxiway to use to get off the runway. The co-pilot spots the sign for Taxiway Delta on the right and as the aircraft approaches, the pilots hear:

CYHZ TWR: "Alpha Romeo Tango, vacate the runway on your first available right and report off this frequency."
FART: "We're approaching Delta and we'll call clear, Alpha Romeo Tango. Lights at minimums on the approach and light to moderate turbulence all the way down."
CYHZ TWR: "Roger, thanks."

When a TWR controller can't see the runway, he may not be able to see where the aircraft actually is on the field. Some high-density or otherwise complex control towers are equipped with ASDE, or Aerodrome Surface Detection Equipment. This is a short range, fast-rotating type of radar that relies on reflected radiation (AKA "skin paint" or, more technically, primary radar) from aircraft and vehicles to show the controllers where everything is. In the absence of ASDE, controllers must keep in the picture of where everyone is, so reports are often requested. In this case, they likely have traffic behind on final, and they need to know when the runway is clear so they can issue a landing clearance to the next aircraft. Since they can't see the runway they ask the KingAir pilots to confirm when they exit.

On another note, pilots will often report "clearing a runway". ATC won't normally use the word "clear" with respect to ground movements, especially on ground frequencies. Past experience has resulted in direction to ground controllers not to use it. Snowplow drivers told to "report clearing the runway" when being told to leave the runway might think, "Hey, I'm clearing the snow off the runway now," and make a report inadvertently leading the controller to believe they are exiting the runway and that it's safe to clear an aircraft to land or take-off. Terms like "exit" or "vacate" are used instead.

FART: "Alpha Romeo Tango is clear of runway two four in Delta"
CYHZ TWR: "Roger. Contact Ground on one two one decimal niner. See ya."
FART: "Alpha Romeo Tango."

Taxiing to Parking

FART: "Ground, Alpha Romeo Tango with you in Delta for IMP."
CYHZ GND: "Alpha Romeo Tango, ground, taxi Delta, Alpha to IMP. Use caution, the south end of the apron is reported as slippery. Report off Alpha."
FART: "Alpha Romeo Tango, thank you."

Pilots are not required to readback taxi instructions unless they contain a "hold short" instruction. And then they are only required to read back the "hold short" and it's condition unless a more detailed reqadback is requested by ground. For example, if they were told to "hold short of the terminal apron", they must stop short in Delta, and they must read that part back to GND. Otherwise, the AIP RAC 4.2.5 states that simply acknowledging the transmission is enough. Any instruction to enter, cross, backtrack or taxi on should be readback for safety's sake. There is nothing to prevent a pilot from reading back every taxiway in a taxi authorization, but it makes for a very busy ground control frequency, especially at larger, busier airports. Readbacks should be kept to a minimum to keep frequency congestion low. It is prefectly acceptable in Canada for a readback of this, "ABC taxi Alpha, Delta, Charlie four, Hotel, India two and Foxtrot, hold short of runway 25," to sound like this, "ABC will hold short of 25."

FART: "Ground, Alpha Romeo Tango is clear of Alpha at IMP. Good day."
CYHZ GND: "Alpha Romeo Tango, roger. So long."

Our pilots leave Alpha taxiway and look for their marshaller and continue into the apron once they see him. They park the aircraft, secure the cockpit and shut down. Landed at last.




Despite winter's nasty weather, out pilots have made it from CYJT to CYHZ safely. What did you think about this mini-series? I'm always happy to read feedback, positive or negative. Please send any comments to me via e-mail at moxner@nbnet.nb.ca. Thanks for following our intrepid pilots through this little "adventure", and I hope you return in the future.