Flying an Approach with only an iPad

You’re suddenly having a bad IFR day. As you approach your destination, Huron, SD, after a routine departure and a comfortable cruise in IMC, most of your panel abruptly goes dark. You still have basic flight instruments, including an electronic PFD and an HSI, which run on backup batteries. Your last communications with ATC included a clearance to an initial approach fix and “expect the ILS RWY 12 approach.” But your GPS navigator, which includes navigation receivers, is now kaput, along with your second nav/com. In other words, you have no moving map or course guidance in the panel–just attitude, airspeed, altitude, and heading. You can’t even see a GPS track indicator.

The good news is, you have an iPad with a built-in GPS (or a tablet connected to an external GPS source) running ForeFlight or a similar app. The EFB confirms that your blue “own ship” symbol is tracking toward HUMSO, an initial approach fix that marks the beginning of a feeder route that takes you to the final approach course.

Using just your track shown on the approach chart, and your basic instrument flying skills, can you fly the approach?

I practice such scenarios periodically during recurrent training. In my A36 Bonanza, operating under VFR with a safety pilot, I switch the navigation screen on my GTN 750Xi to the traffic page, which provides no navigation information, and then I practice getting to an airport and flying an approach using only the iPad for guidance.

Of course, an iPad isn’t a “suitable RNAV system” as defined in the AIM and FAA advisory circulars, but in IMC under IFR, this scenario qualifies as an emergency, and you can bend the rules as necessary to arrive safely.

As you’ll see in this video, a challenge like this is also an excellent workout in an aviation training device. Galvin Flying, the flight school in Seattle where I instruct, has two ATDs made by one-G Simulations. They emulate C172s. You can connect ForeFlight to the Wi-Fi signals broadcast by each trainer, which send position, altitude, speed, and other information to your tablet. As far as ForeFlight is concerned, you’re flying.

Just as in the airplane, provided your EFB can receive GPS signals, you have a good 2-D navigation solution. If you can keep your blue airplane tracking along the lines on a geo-referenced approach chart, you’ll follow the intended path. What you don’t get, however, is any type of vertical guidance. It’s up to you to establish and maintain a steady descent that keeps you as close as possible to an ILS glideslope or a GPS glidepath for an approach to a DA, or to the profile for a non-precision approach to an MDA.

You may also want to practice using the synthetic vision feature, if your EFB app supports it. Although I prefer flying with the procedure chart visible, synthetic vision would be a terrific aid if you lose the basic flight instruments.

Flying an approach like this successfully requires mastery of fundamental instrument skills, what we used to call flying with only “needle, ball, and airspeed.” You must understand and be able to apply the control-performance method of instrument flying—establishing the appropriate attitude, setting power and configuration, monitoring your progress, and making constant, smooth adjustments as you proceed. In other words, it’s a good test that takes you back to drills like flying Pattern A and Pattern B that you practiced early in your IFR training.

Watch the video to see how accurately I flew two approaches in the ATD with just the airplane symbol on an approach chart for guidance.

A Scenic Approach to Boeing Field

I recently flew the A36 Bonanza from Boeing Field (KBFI) in Seattle to Grant County Airport (KMWH) at Moses Lake, WA and back, taking advantage of a break in the weather to cross the Cascade Mountains again before winter weather makes such trips increasingly rare.

The return to KBFI included a visual approach that passed over Seattle-Tacoma International Airport (KSEA) to a swooping descent over Puget Sound and through Elliott Bay to runway 14R.

I also captured videos of the flight to and from KMWH, which you can watch on my YouTube channel here and here.

Mixing RNAV and an ILS

If you fly an airplane with a suitable RNAV system (for most of us, that’s an IFR-approved GPS navigator in the panel), you’re accustomed to flying RNAV (GPS) approaches and other procedures, such as RNAV departures and arrivals. And since most RNAV navigators currently in use also support flying ILS and VOR procedures, you also probably still fly the occasional ILS or VOR approach, even if you prefer all-GPS procedures.

But as the shift to Performance-Based Navigation (PBN) continues, the FAA is publishing more approaches that include–and sometimes require–using both GPS-based RNAV systems and ground-based navaids.

For other examples, see An ILS that Requires GPS, and the ILS OR LOC RWY 21 at KSTE in WI.

Consider the ILS or LOC RWY 12 at Huron (KHON), a small town in South Dakota.

In many respects, this is a typical ILS. It offers a DA at 200 AGL and requires 1/2 sm visibility (the RNAV (GPS) approach to RWY 12 offers the same LPV minimums). It also has an old-school locator outer marker (LOM) at BEADY that serves as the final approach fix for the LOC-only version of the approach and as the anchor for the missed-approach holding pattern.

But read the note in the required equipment box.

In most light aircraft these days, you must also have an IFR-approved GPS to fly the feeder routes and to identify BEADY, because your panel probably doesn’t include DME or an ADF.

ATC could provide vectors to steer you from the enroute environment to the final approach course. But as I’ve noted elsewhere, if you filed IFR as an RNAV/PBN-capable aircraft, a controller can clear you direct to any initial approach or intermediate fix, even if you’re flying a conventional procedure like an ILS.

The enroute chart for the area around Huron shows why you might expect such a clearance. The closest VOR at Watertown (ATY) is nearly 40 nm away, and the airways that converge at KHON are all GPS-based T-routes. The VOR at HON has been decommissioned; only the DME component remains (for more information, see Stand-Alone DMEs on Charts).

A controller can avoid issuing a series of vectors and altitudes as you fly toward the airport and offer one simple instruction, “Cross HUMSO [or WEDEM] at or above 3000, cleared for the ILS RWY 12 approach.”

Your task is to brief the plan for changing from GPS guidance to fly the feeder route from either HUMSO or WEDEM to “green needles” to intercept and track the localizer as you turn inbound toward the airport. And decide, if necessary, how you’ll fly the missed approach.

So today, even if you’re flying to a GA airport far from the big city, you should be prepared to load and fly such hybrid procedures if, for training or practice, you want to fly an ILS, LOC, or VOR approach.

Video: Tips for IFR Flights

Fall weather finally arrived in Seattle, so I took advantage of IFR-and MVFR conditions to fly the Bonanza on a short hop from Boeing Field (KBFI) to Arlington (KAWO).

A glitch meant that I didn’t capture ATC or intercom audio on this flight, so instead this video describes some of the techniques and procedures that I use on a typical IFR flight. And I explain how I dealt with an unexpected curve during the approach at Arlington.

A flight from Boeing Field to Arlington in the Bonanza typically involves only about 20 minutes in the air. Under IFR, it’s important to manage the workload—updating the preflight briefing with the latest information, obtaining an IFR clearance, setting up the airplane and avionics, flying a departure procedure, and being ready to begin an approach as soon as you level off.

For example, before I even start the engine, I call the phone numbers for the ATIS or AWOS at my departure and destination and fill in the ForeFlight scratchpads. That way, I have the basic information and I can quickly confirm the current ATIS letter and update the one-minute weather when I contact ATC before takeoff and as I begin the approach that I want to fly, based on the wind and other details.

See the video for other tips, such as annotating charts and loading–but not activating–approaches.

VNAV with a GFC 600 Autopilot

I recently flew the Beechcraft A36 Bonanza from Boeing Field (KBFI) to Aurora State (KUAO) just south of Portland for system software updates at Pacific Coast Avionics.

The IFR flight was in benign weather, but I did need to fly the RNAV (GPS) RWY 35 approach at KUAO. It was a good opportunity to exercise the VNAV capability of the Garmin GFC 600 autopilot. Enjoy the scenery en route and observe the autopilot in action as I explain and use the VNAV feature.

For more information about using VNAV, see Using VNAV During an Instrument Approach.

The departure was pretty, including a nice view of KSEA, but if you want to focus on the approach, start at about 22:10.

And here’s video of the trip back to KBFI via the LOC RWY 32L approach.

A Low IFR Approach at KOLM

After a long stretch of widespread fog and icy clouds, the skies in the Puget Sound area cleared—mostly—creating a good opportunity to fly an instrument approach in LIFR conditions at Olympia, the state capital southwest of Seattle.

Ride along in this video at my YouTube channel as I make the short hop in the A36 Bonanza from Boeing Field to fly the RNAV (GPS) RWY 17 approach at KOLM.

The approach offers LPV minimums to the same 200 ft DA and ½ mile visibility as the ILS, and I broke out only a couple of hundred feet above the decision altitude.

The sophisticated avionics and Garmin GFC 600 autopilot in the Bonanza make it easy to fly such approaches. But the skies were busy with training flights, and ATC had its hands full. As you’ll see, one confusing instruction from Seattle Approach had me scratching my head until the controller and I got on the same page.

RNP: Performance Monitoring in Light GA Aircraft

The discussion of RNP–Required Navigation Performance– in AIM 1−2−2. Required Navigation Performance (RNP) and other FAA guidance confuses many pilots because the usual definition of RNP focuses on the type of equipment typically installed in bizets and airliners, not light GA aircraft.

Here are the key sentences in that AIM description of RNP:

RNP is RNAV with the added requirement for onboard performance monitoring and alerting (OBPMA). RNP is also a statement of navigation performance necessary for operation within a defined airspace. A critical component of RNP is the ability of the aircraft navigation system to monitor its achieved navigation performance, and to identify for the pilot whether the operational requirement is, or is not, being met during an operation. 

TBL 1-2-1 in the AIM shows the values, in nautical miles, associated with each standard RNP level.

Most GA pilots are concerned with only the RNP APCH (0.3 to 1.0), Terminal (1.0), and En Route (2.0) RNP levels.

For more information about how RNP, RNAV, and related notes are used on IFR approach charts, see Unscrambling RNAV, RNP, and Other Chart Naming Conventions and Notes here at BruceAir.

Unlike the FMS and other equipment in jets, the displays in the suitable RNAV systems (i.e., GPS and WAAS navigators) and PFDs installed in our aircraft usually don’t show numerical values for RNP levels. So how you verify that your system is achieving the required navigation performance during different phases of flight?

The avionics common the light GA world typically annunciate RNP status by displaying ENR, TERM, LNAV, LPV, LP, etc., as described in the tables below from the Garmin Pilot’s Guide for the GTN series (190-02327-03D).

These letter-based RNP annunciations typically appear on the PFD near or within the HSI and on the screen for the navigator, as shown in the examples below.

A table below from the Pilot’s Guide for the Garmin G500 Txi (190-01717-10 Rev. J). provides similar information.

The LNAV, LNAV+V, LPV, LP, LP+V, and (rarely LNAV/VNAV or L/VNAV) annunciations are associated with the RNP APCH level, which is 0.3 nm for basic lateral navigation and is also used for the tighter, angular courses defined for the localizer-like final approach segments established for approaches with LPV and LP minimums.

FAA is preparing a new advisory circular, AC 90-119, which should consolidate and clarify guidance about performance-based navigation (PBN), RNAV, RNP, and related topics in one document. I submitted comments asking that tables like those above be included in the sections that define RNP values and explain how typical GA pilots can meet the requirement to monitor RNP while operating under IFR.

For a detailed look at the draft of the new AC and to see my comments, see Draft AC 90-119 Performance-Based Navigation Operations here at BruceAir.

Unscrambling RNAV, RNP, and Other Chart Naming Conventions and Notes

Many pilots are confused by the terms RNAV, RNP, and RNP APCH that appear on instrument approach charts, and it’s easy to see why.

Although ICAO is adopting a new naming standard as the world shifts to Performance Based Navigation, or PBN, the FAA is sticking to its conventions. And that approach leads to some terms having more than one meaning or to blurring important distinctions.

This video below takes a closer look at what those abbreviations, initialisms, and notes mean.

You can watch videos on other topics at my Presentations for Pilots playlist on YouTube.

For more information on this topic, see:

Part 91 IFR Takeoff Minimums

A colleague recently pointed me to an article (Takeoff in Dense Fog…) at boldmethod that argues that the IFR takeoff minimums listed on IFR charts apply, even to operations under Part 91, if you accept a clearance that includes a DP, ODP, or SID.

But in most cases, these IFR takeoff minimums do not apply to pilots flying under Part 91EXCEPT if the pilot is assigned and accepts a published departure procedure that includes takeoff minimums.

boldmethod 12/30/2017

The article references 14 CFR § 91.175 Takeoff and landing under IFR, specifically the standard takeoff minimums listed in paragraph (f).

Paragraph (f)(1) of the regulation notes:

Unless otherwise authorized by the FAA, no pilot may takeoff from a civil airport under IFR unless the weather conditions at time of takeoff are at or above the weather minimums for IFR takeoff prescribed for that airport under part 97 of this chapter.

But the text that introduces paragraph (f) also specifically notes that:

This paragraph applies to persons operating an aircraft under part 121, 125, 129, or 135 of this chapter.

14 CFR § 91.175 Takeoff and landing under IFR

In other words, those minimums do not apply to operations under Part 91. As explained in the Landis Letter (1999) [PDF], a letter of legal interpretation from an attorney at the FAA:

…Section 91.175(f) further states that no pilot operating an aircraft under Parts 121, 125, 127, 129, or 135…may takeoff from a civil airport under IFR unless the weather conditions are at or above the weather minimum for IFR takeoff prescribed for the airport under Part 97.

My research has indicated that when section 91.116(c)–the predecessor to the current section 91.175–was first proposed for adoption in 1967, this issue arose and was addressed as follows: Several comments indicated that section 91.116(c) of the proposal could be interpreted to apply civil airport takeoff minimums to aircraft operators other than those operating under Part 121, 129, or 135. As this result was not intended [underline added], the language of the paragraph as adopted herein has been changed to make it clear that the minimums apply to aircraft operating under 121, 129, or 135 (32 FR 13909 Oct 6, 1967). Accordingly, I am constrained to agree with your analysis that a Part 91 flight can depart in weather conditions less than the minima prescribed for the SID.

Note that the letter above does not mention Part 91K, which applies to Fractional Ownership Operations. Those operations are subject to additional constraints described in the management specifications FAA approves for each operator.

And that legal interpretation does not address the wisdom of departing in LIFR–perhaps zero-zero conditions–even if a close reading of the regulations allows it when you’re operating under Part 91.

Many experts recommend that you depart IFR only if weather at the airport you’re leaving is at least at or above the minimums for an approach at that airport, should you need to return quickly after takeoff. Some folks go further and use the circle-to-land minimums as their baseline. Or they plan for a takeoff alternate, which also isn’t required for Part 91 operations, but is always prudent.

Handling a ‘Random Radial’ Clearance

I recently rode along on an IFR flight that involved an amended clearance during the descent and arrival that pointed out a challenge you may encounter while flying with GPS as your primary navigation source.

The original IFR clearance received before departure ended with a leg from the Beatty VOR (BTY) northwest of Las Vegas, NV direct to the destination, Boulder City Municipal Airport (KBVU).

As we approached BTY, ATC complicated matters with the following amendment:

BTY V135 HIDEN BLD R256 BLD

In plain language, after BTY, we were to join V135, fly to the HIDEN fix, track the 256 radial inbound to the Boulder City VOR (BLD), and finally fly direct to our destination.

The pilot flying was displaying only the magenta CDI that showed us tracking the original route, so the challenge after adding the leg to HIDEN, which could easily be flown while still using GPS, was how to intercept and fly the leg inbound on the 256 radial to BLD. That radial doesn’t correspond to an airway or other defined track on the enroute chart or the chart for the RNAV (GPS) RWY 27 approach at KBVU.

The temptation is to try to build a flight plan leg that defines the inbound course (076) to the VOR. If you have time to set it up, you have a couple of options, such as setting a course to a fix or perhaps creating a user waypoint and adding a leg to the flight plan.

But we were in a speedy descent, already close to BTY. To ensure that we didn’t blow through the radial when we reached HIDEN, I suggested a simple method to help us stay on track until we could reprogram the navigator: Use a bearing pointer tuned and set to the BLD VOR.

For more information about bearing pointers, see the Using Bearing Pointers-Part 1 and Part 2 at my YouTube channel, BruceAirFlying.

That technique allowed us to add HIDEN to the flight plan and continue using GPS to fly along V135.

Using a bearing pointer also meant we wouldn’t have to switch CDI sources as we intercepted the radial. Changing the CDI from GPS to NAV (or vice versa) typically also causes the AP to revert to roll mode, which can lead to “What’s it doing now?” confusion on the flight deck.

Approaching HIDEN we could instead deliberately change the AP to HDG mode, and, using the bearing pointer, intercept the radial inbound to BLD. Once established on the radial, we could confirm that we’d set up the proper course or add a leg to BLD and then continue using GPS in either NAV or LNAV mode (depending on the autopilot) to fly the amended route.

As we approached HIDEN, we watched the tail of the bearing pointer rise toward 256, and as it crossed about the 260 mark, we began a left turn toward the head of the arrow to track the 076 course inbound to BLD.

Once established on the 256 radial, we could have set a direct-to course of 076 to BLD and changed the AP back to NAV/LNAV mode and used GPS to fly to the VOR as cleared.

But as is often the case, ATC started issuing vectors, and we never flew to BLD.

Newer versions of a Garmin PFD, such as the G500 Txi, offer another option—a VOR course preset.

From the Garmin G500 Txi Pilot Guide

If your avionics offer this feature, when the CDI is set to GPS guidance, but you anticipate joining a VOR radial or localizer, you can preset the navaid course you intend to intercept and track. The course preset appears in a window below the HSI.

As you approach the intercept, change the AP/FD to HDG mode (to avoid a sudden turn or change to AP roll mode), then switch the CDI to VOR/LOC. The course arrow will already be set to the course you want to fly. No need to twist the course knob. Fly the appropriate heading to smoothly intercept the VOR/LOC, and continue on your way.

Note that you may see a small difference between GPS and VOR courses as you track a radial. That’s a normal and expected consequence of how different navigation systems apply magnetic variation, as explained in AIM 1−1−17. Global Positioning System (GPS) , paragraph k. Impact of Magnetic Variation on PBN Systems. Either navigation system will guide you along the correct track.

An ATD or simulation such as the free Garmin PC Trainer Suite is an excellent tool to help you practice how to cope with a clearance that involves intercepting a “random radial” and avoid a scramble to comply during a high-workload phase of flight.