By the Book

In last month's discussion of "Preflight Action," We stressed the importance of pilots' fully exploiting the notam system for the latest information that could affect the safe outcome of a flight. This is easier said than done. Notices to airmen appear in a number of formats and must be gathered from a variety of sources. Efforts to streamline the notam system are under way, but in the meantime, pilots are obliged to understand and use the existing system, cumbersome — and confusing — as it may be.

Technically, a notam is "a notice containing information (not known sufficiently in advance to publicize by other means) concerning the establishment, condition, or change in any component (facility, service, or procedure of, or hazard in, the National Airspace System [NAS]) the timely knowledge of which is essential to personnel concerned with flight operations."

That's the definition provided in the Airman's Information Manual, Air Traffic Control Handbook, and Flight Service Handbook. But notams also include information so temporary in nature that it wouldn't make sense to publish it on a chart or in an Airport/Facility Directory.

Officially, three categories of notams have been established: notam (D), notam (L), and FDC notam. In reality, a fourth category, "special notices," also exists. In addition are international notams, published biweekly in International Notices to Airmen and also available from your flight service station or the U.S. International Notam Office in Washington, D.C., but we'll focus on the domestic variety.

You will sometimes hear references to "Class II" notams, though seldom to "Class I" notams. "Class" refers to the categorization of notams by the International Civil Aviation Organization. ICAO defines a Class I notam as one distributed through a telecommunications medium; Class II, "by means other than telecommunications."

When someone speaks of a Class II notam, they usually mean one published in the Notices to Airmen publication (NTAP).

Notams are distributed in a variety of ways, including the so-called "Service A" telecommunications system; telephone, radio, or personal contact with an FSS; the Direct User Access Terminal (DUAT) system; the NTAP; transcribed weather broadcasts (TWEBs); unscheduled FSS broadcasts; and commercial weather briefing and flight planning services.

Notam (D), for distant, information is disseminated for all navigational facilities of the NAS and for all public-use airports, seaplane bases, and heliports listed in the A/FD. This can include data on airports, airport operating restrictions, control zones, runways, runway edge light systems, approach light systems, airport traffic control towers, FSSs, and weather observing systems. The database is maintained on a computer at the National Communications Center in Kansas City, from which distant notams are distributed automatically, appended to hourly weather reports, over Service A to FSSs and other air traffic facilities. These notams are available through Service A until they are published in the NTAP. Because DUAT uses Service A, distant notams are also available through that medium. If you get a standard weather briefing from an FSS, you will automatically be provided the available distant notams.

Notams relating to loran chain or station outages, by the way, are issued as notam (D)s under the identifier LRN. International notams relating to loran are issued under the KNMH identifier. If you use the Omega navigation system, you should request notams by Omega station name. No notams are issued for the U.S. Navy's VLF (very low frequency) system, but information is available from the Naval Observatory (telephone 202/653-1757).

Notam (L), or local, information is not as widely disseminated as distant notams. A file of local notams is kept by each FSS for facilities in its area only. This information may include such items as taxiway closures, men and equipment near or crossing runways, airport rotating beacon outages, and data pertaining to airport lighting aids, such as VASIs, that do not affect instrument approach criteria. An FSS will give you local notam information, but if your flight will take you out of that FSS's jurisdiction, you must call ahead to the appropriate FSS for local notams. The DUAT service is not required to provide local notams.

FDC notams are regulatory in nature and are distributed by the National Flight Data Center in Washington, D.C. They concern things like changes in instrument approach procedures and aeronautical charts. They are also used to highlight temporary flight restrictions due to, for example, natural disasters or large-scale public events that might generate air traffic congestion. (Temporary flight restrictions will be discussed in detail in a future "By the Book.") FDC notams are transmitted over Service A just once and then are kept on file at FSSs within 400 miles of the subject site until they are published or canceled. (Note: FDC notams for temporary flight restriction are not published but may appear as a special notice.) "Local" FDC notams will be given to a pilot during a standard weather briefing, but FDC notams concerning conditions more than 400 miles distant or that have been published will be given only upon request. DUAT provides FDC notams only upon site-specific request using a location identifier.

Let's recap. For a cross-country flight, you'll need to make at least two calls to FSSs to get all the necessary local notams to satisfy the regulation concerning preflight action. Available distant notams and "local" FDC notams are offered by your FSS until published in the NTAP, the contents of which are furnished only on request (or by subscription, but not many pilots, unfortunately, go to this length).

Because the NTAP is the notam source least familiar to most pilots, a closer look is in order.

The NTAP is published every two weeks. On the contents page of the NTAP is noted the number of the last FDC notam included in the publication. The March 19, 1992, NTAP, for example, says, "FDC notams listed through 2/1314, dated March 5, 1992." The numbering system doesn't tell you much — it's simply a sequential code assigned to the message originator — but you can use the numbers and date to identify notams that were issued after the cutoff date for inclusion in the NTAP. Information remains in the NTAP until it expires, is canceled, or is published elsewhere, such as the A/FD or aeronautical charts. New items in each NTAP are identified by a vertical bar in the adjacent margin. NTAP notams are not carried on Service A and are not provided during FSS weather briefings except upon request. They do not appear on DUAT.

The NTAP is divided into two sections. The first contains distant notams that are expected to remain in effect for an extended time (at least seven days after the effective date of the NTAP) and FDC notams current at the date of publication. On occasion, a local notam will be included if it has a significant bearing on flight safety. Data are grouped into categories such as airways, chart corrections, flight advisories, flight restrictions, airports, facilities, procedural notams, and so on. Airways and flight restriction notams are arranged by state and in descending numerical order. Airports, facilities, and procedural notams are arranged by state, city, and airport or facility name.

The second section contains the special notices alluded to earlier. These are generally too long, concern too large or unspecified a geographic area, or "don't meet Section One criteria." The NTAP says special notices "MUST have a significant impact on FLIGHT SAFETY to be carried." (Nevertheless, there's some pretty strange stuff in this section with only the most tenuous connection to safety, as we'll see.) In other words, section two of the NTAP is a catchall.

Let's look at some examples. Here's one from section one, the airways category, under the heading "Florida, Georgia":

FDC 1/5603 FI/T/AIRWAY/FL/GA. V441 MONIA INT, FL TO BRUNSWICK (SSI) VORTAC, GA, MOCA 2500.

The format is pretty straightforward, advising us of the minimum obstruction clearance altitude for a segment of an airway. The one item of real interest is the FI/T, which means "flight information/temporary." You will also see FI/P, with the P meaning permanent."

Here's a simple one from the airports/facilities/procedural notams section, under "California, Angel's Camp, Angel's Camp RCO": FREQ 122.3 CMSND.(2/92)

This one, you will note, is not an FDC notam. More typical is the following, noting a change in an ILS procedure at "Florida, Fort Lauderdale, Fort Lauderdale-Hollywood Intl" (note that it is a permanent change):

FDC 2/1209 /FLL/ FI/P FORT LAUDERDALE-HOLLYWOOD INTL, FORT LAUDERDALE, FL. ILS RWY 27R AMDT 4 ... TRML ROUTE FLL VOR/DME TO JUMAR INT MIN ALT 4000. TRML ROUTE BSY VORTAC TO JUMAR INT MIN ALT 4000. CIRCLING MDA CAT D 700 HAA 689. VIS CAT D 2 1/4. ILS ALT MINS CAT D 700-2 1/4. MISSED APCH: CLIMB TO 4000 VIA FLL R-270 TO PIONN INT/FLL 10.9 DME AND HOLD. THIS BECOMES ILS RWY 27R AMDT 4A.

The commissioning of a new remote communications outlet is nice information to have. Significant changes in an instrument approach procedure, however, represent information we'd want to be sure we had. Indeed, this edition of the NTAP notes seven new changes to instrument approaches at FLL.

Turning to section two, we find categories including international advisory, airport advisory, GPS advisory, airspace designation, flight plan requirements (one entry for each of those), loran advisories (five entries), flight advisories (six), radar advisories (one), flight restriction (five), laser light demonstration (one), remote piloted vehicle flights (two), special demonstrations (nine), warning areas (one), special-use airspace — military operations (two), special traffic management programs (six), and special Sun 'n Fun fly-in.

Special notices can be short. The GPS advisory reads, in its entirety, "Until the Federal Aviation Administration (FAA) approves the United States Global Positioning System (GPS) for civil use, GPS does not meet the requirements of civil aircraft for instrument flight rules (IFR) flights." Most everyone knows this; it's here, in the NTAP, to make it official.

Special notices can be lengthy, too. The Sun 'n Fun entry, for example, runs 17 pages.

And most of the information is indisputably essential to safety. A pilot should certainly want to know, for example, that "the radar energy transmitted by the USAF Pave Paws [and] over-the-horizon backscatter radar system [s] " at Moscow, Maine; Cape Cod, Massachusetts; Christmas Valley, Oregon; and San Angelo, Texas, "create a hazard to people and aircraft." Ditto that the laser light experiment at Arecibo Observatory in Puerto Rico "may be injurious to pilot's/passenger's eyes."

It makes fascinating reading, but the connection to safety is sometimes thin. The international advisory, for example, notes that private aircraft landing at Mexico City Airport will be charged a $1,256 landing fee (the fee has been reduced; see "AOPA Direct," p. 11). It's undeniably valuable information, and the luckless pilot who learns it the hard way might find a subscription to the NTAP ($79 a year) cheap by comparison, but the only significant safety question may be the fate of the customs official who tries to collect the fee.