Those of you missing Carlo will be bemused to know that he is cramming for his radio operator’s license exam tomorrow and his Private Pilot License written exam next week. He just completed his 40 flight training hours. His Student Pilot License expires on May 30. He needs to focus on getting his PPL before then. He has also enrolled in summer classes, to try and get ahead of his senior year load at the Ateneo.
He will be back soon, on these pages.
Most general aviation(non-scheduled, non-airline) flights are flown under Visual Flight Rules, or VFR. The pilot looks out the window during the whole flight, glancing at his instruments only to assess his airplane performance and to check his navigation. His primary navigational tools are his eyes, and the view outside. He looks for towns, rivers and other landmarks, comparesthose to his chart, and finds his way along his planned route of flight, checking his compass every now and then to verify that he is indeed going the right way. Under VFR, the pilot is solely responsible for maintaining ‘separation’ from other traffic. He must use his eyes to see and avoid other airplanes in flight.
This is how the early airplanes were flown. This is still how pilots learn to fly. And this is still the way for most general aviation flights. Aerobatics, fire-fighting, traffic monitoring, aerial photography, most military training, aerial tours — all of these are moot if you can’t see outside.
The minimum visibility required to legally fly under Visual Flight Rules is 8 kilometers — 5 miles.
When the weather is bad, the pilot cannot see the towns, rivers and other landmarks. So in cloudy, rainy or hazy weather, he flies under Instrument Flight Rules, or IFR. When flying IFR, the pilot is in constant touch with Air Traffic Control, or ATC, which tracks him manually, or on radar. Air Traffic Control has responsibility for maintaining separation between the airplane and other airplanes who are also flying under IFR. That’s because in bad weather, the pilot cannot be expected to see other airplanes.
There are instruments in the cockpit that a pilot uses to fly under IFR. He has an artificial horizon or Attitude Indicator (AI), which tells him how the real horizon outside looks like if he could see it. Blue sky above, brown earth below. This instrument, is only 3 inches in diameter — a tiny substitute for the real world outside.
He has a Vertical Speed Indicator, or VSI, which tells him if he is going up or down, and how fast. He also has a Directional Gyro Compass, or DG, which tells him which direction he is going. Hehas an altimeter, which tells him how high he is flying. He has a Turn Coordinator, which helps him fly in a standard-rate turn, one that will move his nose around the compass at a predictable rate that can actually be timed. And he has an Airspeed Indicator, or ASI, which tells him how fast he is flying.
He has navigational instruments too. There is a navigational radio with a VOR display. If the pilot tunes to a Very high Omnidirectional Range (VOR) radio station is, the display will allow him to track to or from the VOR station along a chosen compass direction, or bearing. A CDI, or Course Deviation Indicator bar, shows how far he is from his desired track. If he centers the bar, he is on track
He also has an Automatic Direction Finder, or ADF, which is another radio receiver also with a display. The ADF display has a needle which points directly to a Non-Directional Beacon (NDB) or a commercial radio station. If a pilot tunes his ADF radio to that station, the needle will show him the way there.
Finally, he has a watch, or a clock. Instruments, radios and radio stations do fail, and a real test of instrument flying skill is the ability to fly ‘partial panel’, with one or more of the instruments not working. So if his altimeter is broken, for example, the pilot can time hisVSI and fly from one altitude to another. If his DG is broken, he can still use his Turn Coordinator to establish a standard-rate turn, where the airplane is turning 3 degrees per second (yup, that’s a full circle in two minutes). Given that he knows where he was originally pointed, he can turn to another compass heading by timing his standard-rate turn.
Instrument flight requires a lot of learning. One must take a 40-hour classroom course, and then fly a simulator or an airplane for 10 hours, and complete another 30 hours in an airplane. During that time he wears a ‘hood’, like a baseball cap with a very long bill, so that he can see just his instruments, and not the view outside. An instrument-rated instructor sits beside him in the cockpit. The instructor can look outside and monitor the instruments to ensure that the pilot does not kill them both by hitting an unseen mountain, or the ground.
An instrument-rated pilot is expected to be able to find his way from an airport, along various waypoints on a pre-determined path, navigate to another airport, position his airplane on an approach path to the unseen runway, and fly that approach, bringing his airplane so close to the runway lights so that, even in bad weather, he can then look up and see his way down the last few hundred feet to the runway. All this without looking outside. Looking only at the 3-inch diameter instruments in front of him.
Learning the jargon alone is daunting. In technical terms, the paragraph above means he can fly a Standard Instrument Departure (SID), navigate along an airway, fly an Standard Terminal Approach Route (STAR) or obey radar vectors from ATC, such that he gets to the Initial Approach Fix (IAF) of an instrument approach procedure.
Then he must be able to fly a ‘letdown’ procedure that will bring him to a Final Approach Fix (FAF) where he is pointed at the unseen runway many miles away, fly an instrument approach by homing in on VOR or NDB radio beacon or by following the radio signals of an Instrument Landing System (ILS), and fly safely down to a Decision Altitude (DA) or a Minimum Descent Altitude(MDA), usually only a few hundred feet above the unseen ground.
All by instruments, without looking outside.
At the DA, if he looks up and sees the runway through rain, or clouds, or fog, he can then fly visually and land the airplane. If, at the DA, he cannot see the runway or the runway approach lights, he must execute a missed approachand continue to fly the airplane solely by instruments back to the IAF for another try.
He can keep on doing this until he runs out of fuel. The preferred alternative is to use the fuel to fly to an alternate airport where the weather is better.
Airports which have the necessary ATC and radio navigational aids for instrumentapproaches are few and far between, in this country. Most airports and airfields are VFR-only — no instrument approach procedures, no Air Traffic Control except for a control tower, no SIDs, no STARs, no runway lights, even. To use an airport under VFR, you have to be able to see it from 8 kilometers away — 5 miles.
So when the weather turns bad, and visibility drops below 8 kilometers, pilots who are not instrument rated cannot fly. If they are already flying, they must not fly into IMC, instrument metereological conditions,where IFR flight is mandatory. Pilots who are not instrument rated must fly in VMC, visual metereological conditions — away from clouds, in 8 kilometers of visibility. Attempting to fly visually in IMC is statistically the NUMBER ONE cause of fatal accidents in general aviation.
It takes years to gain real IFR proficiency. It takes many hours simply to get used to flying the airplane blind. It takes as many hours to learn how to talk to ATC. It takes days to understand instrument approach charts, or plates. It takes weeks of classroom work to understand the rules by which he can fly blindly, make his way to an unseen runway, and execute the approach to that runway without hitting the terrain, or losing control of the airplane.
An IFR airport has many instrument approach procedures, STARs, and SIDs, each with its own chart. Which one is in use depends on the surface wind, the availability of the navigational aids, and ATC. The pilot must be familiar with them all. He must have every chart in his flight bag or kneeboard. There is no telling which procedure he might have to use, at his planned destination. He will only find out when he gets close. It depends on … the weather.
Tough? Trusting that the airplane is right side up without looking outside is probably the scariest thing of all. Ask me how I know this.
Carlo and I flew to the former Cubi Point Naval Air Station, at what used to be the US naval base at Subic Bay. It’s now the Subic International Airport, the regional hub of Federal Express in Asia, and is surrounded by high mountains, up to 5,000 feet high. We departed Omni Aviation an hour before sunset. It takes about an hour to get to Subic, and another hour to fly back to Clark. We were in RP-C391, a fuel-injected, 190 horsepower Cessna 172XP, fully IFR-equipped, dual navigation and communication radios, strobes, the works.
Omni Aviation is located within the Diosdado Macapagal International Airport, at the old US Air Force Base known as Clark Field. Nobody really calls it the Diosdado Macapagal International Airport. We all say “Clark” on the radio.
The small Omni Aviation airstrip is only several hundred meters away from the main Clark runways. Omni is a VFR-only airfield. It does not have an SID, or Standard Instrument Departure. An SID is a standard routing for flights that are departing an airport under IFR.
The picture on the left shows the main runways of Clark, which used to be one of the most secret spots on earth. The Omni Aviation runway is the tiny asphalt runway with the piano bars, barely visible at the extreme lower left corner, beside the 3 mango trees….
So I asked Clark Tower for a clearance to take off under VFR from Omni, return to CIA, the VOR navigational beacon at Clark, climbing to 7,000 feet, then track outbound under IFR on the CIA 218 radial to KIBOK intersection, where the Clark Terminal Maneuvering Area ends and the Subic TMA begins. KIBOK marks the point where Clark’s Air Traffic Control responsibility for our flight would end, and where Subic ATC would take responsibility for us.
My requested clearance was in fact identical to one of the Standard Instrument Departures at Clark, except that I would be flying it visually, VFR, from the VFR-only airfield of Omni.
Surprisingly, Clark Tower issued us a clearance for an instrument departure.
“RP-C Three Niner One, you are cleared via SID 29 to KIBOK, climb and maintain 7,000 feet to KIBOK, squawk one one zero nine.”
I read back the clearance, and we were told to report airborne from runway 20 Omni.
SID 29 required me to takeoff, climb straight out on the runway heading to 3,000 feet, then make a left climbing turn back to the CIA VOR, climbing still, to cross the VOR at or above 7,000 feet as cleared by ATC, then track the CIA 218 radial to KIBOK intersection, maintaining 7,000 or higher as assigned by ATC. The minimum crossing altitude(MCA) at KIBOK is 7,000 feet. Click on the chart to see SID 29.
Did I mention that there were mountains all around Subic?
Well, there are mountains all around Clark too, especially to the west and south. In fact Mt. Pinatubo (see Flying Into A Volcano) is southwest of Clark. Subic, our destination, is southwest of Clark also. Mt. Pinatubo is around 5,000 feet high. Hence the MCA of 7,000 feet on the chart.
There is a mountain east of Clark also — Mt. Arayat, 3,000 feet high. Hence the initial climb requirement on the SID — climb straight out to 3,000 feet [so that you are higher than Arayat, doofus!] and only then turn left back to the VOR. And be at 7,000 over the VOR so that you are higher than Pinatubo, in case you stray westbound as you turn southwest to Subic.
See how SIDs are designed? If you follow them religiously, you are protected from the terrain.
We were climbing straight out to 3,000 feet when Clark Tower told us to switch to Clark Approach. We were leaving the tower’s control zone.
“Three Nine One contact Clark Approach now, one one nine two.
“Switching, Three Niner One, good day sir.”
I switched the Comm 1 radio to 119.2 and called Clark Approach.
“Clark Approach, Three Niner One with you runway heading climbing to 3,000, cleared for SID two nine.”
Clark Approach had an immediate surprise for us.
(to be continued…)
This is the first of three parts on IFR flights with Carlo. I’ll work on each part as Carlo works on his PPL. I suppose after he passes his check ride he will have a dozen pages to write! Me, I’m waiting to write about my first flight with Carlo as Pilot in Command. That should be a hoot!
Feel free to comment or ask questions about IFR flight. Someone may actually have a correct answer!