How'd this guy go?

[flyingcheesehead]

So, the 121 ops can't shoot an approach when the weather is reported below minimums, right? Or does that only apply to visibility?

I was looking at weather to see if it was good enough that I could shoot some approaches and still make it back in... And it appeared not. This is the METAR and TAF that was active when Eagle Flight 4237 took off at 2049Z:

KMSN 312021Z 17006KT 1/4SM BR OVC001 06/06 A2960 RMK AO2 SFC VIS 3/4

KMSN 311905Z 3119/0118 VRB03KT 1/4SM FG VCSH OVC001
TEMPO 3122/3124 1/2SM FG OVC002
FM010000 19010KT 3/4SM BR OVC003
FM010200 21012KT 3SM BR SCT006 BKN010
FM010800 21015G25KT P6SM SCT020

So, both ceiling and vis below ILS minimums (all we have here is category 1). Tower Vis at 3/4, though. But, the forecast also doesn't show the prevailing conditions to go above mins until 0000Z, and only temporarily after 2200Z.

The following 2 METARs were issued while EGF4237 was in flight:

KMSN 312053Z 17006KT 1/4SM BR OVC001 07/07 A2960 RMK AO2 SFC VIS 2 SLP028 60000 T00670067 55025

KMSN 312100Z 18005KT 1SM BR OVC001 07/07 A2959 RMK AO2 SFC VIS 2

So, by the time they shot their first approach, the vis was reported above mins, but the ceiling still below. So is it only visibility that's required to be reported above mins for Part 121?

FWIW, they shot the ILS 18, and went missed at about 800 feet because they went full deflection on the localizer. (They reported to tower that there was something wrong with the localizer, "It went full deflection and we were on a pretty stable course.") So, they got vectored back around and shot the ILS 21 which has slightly higher mins (1137 1/2 vs. 1060/24 for the ILS 18) due to the offset localizer. But I guess they made it, I haven't heard them on frequency again.

 

[elmetal]

So, the 121 ops can't shoot an approach when the weather is reported below minimums, right? Or does that only apply to visibility?

Don't they get the same treatment where if they see the rabbit they can go down to 100 and then they may have broken out and seen the runway?

Or do you mean that they shouldn't (legally speaking) have even attempted the approach?

 

[Dave Theisen]

Visibility is the controlling factor. If they have the reported visibility, they can shoot the approach even if the ceiling is reported below minimums.

 

[taters]

Visibility is the controlling factor. If they have the reported visibility, they can shoot the approach even if the ceiling is reported below minimums.

As long as they are past the FAF, they can still shoot the approach even if the vis is reported below mins.

Also RVR 1800 with AP/FD on ILS 18 ..I would bet more than that was being reported by tower at the time

 

[Greg Bockelman]

Visibility is controlling. Ceiling is not. Unless some chart somewhere says that ceiling is controlling, but most of the time not.

 

[RotorAndWing]

So, the 121 ops can't shoot an approach when the weather is reported below minimums, right? Or does that only apply to visibility?


So, by the time they shot their first approach, the vis was reported above mins, but the ceiling still below. So is it only visibility that's required to be reported above mins for Part 121?

Visibility is controlling. For takeoff Part 121 can have in their OpSpecs reduced Take Off mins, such as 500/500/500 on the RVR.

 

[Arnold]

Dispatch is governed by forecast or actual weather, proceeding beyond the Final Approach Fix is governed by actual weather, landing is governed by eyeballs - part 135 and 121 must land in the touchdown zone.

See FAA Instrument Procedures Handbook Chapter 5, pertaining to approaches:

PART 91 OPERATORS
According to Part 91.103, the pilot in command must
become familiar with all available information concerning
a flight prior to departure. Included in this
directive is the fundamental basis for pilots to review
NOTAMs and pertinent weather reports and forecasts
for the intended route of flight. This review should
include current weather reports and terminal forecasts
for all intended points of landing and alternate airports.
In addition, a thorough review of an airport’s current
weather conditions should always be conducted prior
to initiating an instrument approach. Pilots should also
consider weather information as a planning tool for fuel
management.
For flight planning purposes, weather information
must be reviewed in order to determine the necessity
and suitability of alternate airports. For Part 91 operations,
the 600-2 and 800-2 rule applies to airports with
precision and nonprecision approaches, respectively.
Approaches with vertical guidance (APV) are considered
semi-precision and nonprecision since they do not
meet the International Civil Aviation Organization
(ICAO) Annex 10 standards for a precision approach.
(See Final Approach Segment section later in this
chapter for more information regarding APV
approaches.) Exceptions to the 600-2 and 800-2 alternate
minimums are listed in the front of the National
Aeronautical Charting Office (NACO) U.S. Terminal
Procedures Publication (TPP) and are indicated by an
“ ” symbol on the approach charts for the airport.
This does not preclude flight crews from initiating
instrument approaches at alternate airports when the
weather conditions are below these minimums. The
600-2 and 800-2 rules, or any exceptions, only apply to
flight planning purposes, while published landing minimums
apply to the actual approach at the alternate.

PART 135 OPERATORS
Unlike Part 91 operators, Part 135 operators may not
depart for a destination unless the forecast weather
there will allow an instrument approach and landing.
According to Part 135.219, flight crews and dispatchers
may only designate an airport as a destination if the latest
weather reports or forecasts, or any combination of
them, indicate that the weather conditions will be at or
above IFR landing minimums at the estimated time of
arrival (ETA). This ensures that Part 135 flight crews
consider weather forecasts when determining the
suitability of destinations. Departures for airports
can be made when the forecast weather shows the
airport will be at or above IFR minimums at the
ETA, even if current conditions indicate the airport
to be below minimums. Conversely, Part 135.219
prevents departures when the first airport of intended
landing is currently above IFR landing minimums,
but the forecast weather is below those minimums at
the ETA.
Another very important difference between Part 91
and Part 135 operations is the Part 135 requirement
for airports of intended landing to meet specific
weather criteria once the flight has been initiated. For
Part 135, not only is the weather required to be forecast
at or above IFR landing minimums for planning a
departure, but it also must be above minimums for initiation
of an instrument approach and, once the
approach is initiated, to begin the final approach segment
of an approach. Part 135.225 states that pilots
may not begin an instrument approach unless the
5-5
latest weather report indicates that the weather conditions
are at or above the authorized IFR landing
minimums for that procedure. Part 135.225 provides
relief from this rule if the aircraft has already
passed the FAF when the weather report is received.
It should be noted that the controlling factor for
determining whether or not the aircraft can proceed
is reported visibility. Runway visual range (RVR),
if available, is the controlling visibility report for
determining that the requirements of this section
are met. The runway visibility value (RVV),
reported in statute miles (SM), takes precedent over
prevailing visibility. There is no required timeframe
for receiving current weather prior to initiating the
approach.

PART 121 OPERATORS
Like Part 135 operators, flight crews and dispatchers
operating under Part 121 must ensure that the appropriate
weather reports or forecasts, or any combination
thereof, indicate that the weather will be at or above the
authorized minimums at the ETA at the airport to which
the flight is dispatched (Part 121.613). This regulation
attempts to ensure that flight crews will always be able
to execute an instrument approach at the destination
airport. Of course, weather forecasts are occasionally
inaccurate; therefore, a thorough review of current
weather is required prior to conducting an approach.
Like Part 135 operators, Part 121 operators are
restricted from proceeding past the FAF of an
instrument approach unless the appropriate IFR
landing minimums exist for the procedure. In addition,
descent below the minimum descent altitude
(MDA), decision altitude (DA), or decision height
(DH) is governed, with one exception, by the same
rules that apply to Part 91 operators. The exception is
that during Part 121 and 135 operations, the airplane
is also required to land within the touchdown zone
(TDZ). Refer to the section titled Minimum Descent
Altitude, Decision Altitude, and Decision Height later
in this chapter for more information regarding MDA,
DA, and DH.

 

[HPNPilot1200]

As others pointed out, visibility is controlling. Ceiling means nothing from a regulatory standpoint with regard to beginning the approach. In reality, reported ceiling allows us to estimate where we might break out. Inside the FAF (or glideslope intercept on an ILS), you can continue the approach when visibility is reported above minimums.

Clay mentioned RVR 1800 required for the ILS 18 with FD or AP or HUD to the DA which is an important to point out. Also note that centerline and touchdown zone lights are required to reduce visibility mins to RVR 1800.

 

[bobmrg]

So, the 121 ops can't shoot an approach when the weather is reported below minimums, right? Or does that only apply to visibility?

I was looking at weather to see if it was good enough that I could shoot some approaches and still make it back in... And it appeared not. This is the METAR and TAF that was active when Eagle Flight 4237 took off at 2049Z:

KMSN 312021Z 17006KT 1/4SM BR OVC001 06/06 A2960 RMK AO2 SFC VIS 3/4

KMSN 311905Z 3119/0118 VRB03KT 1/4SM FG VCSH OVC001
TEMPO 3122/3124 1/2SM FG OVC002
FM010000 19010KT 3/4SM BR OVC003
FM010200 21012KT 3SM BR SCT006 BKN010
FM010800 21015G25KT P6SM SCT020

So, both ceiling and vis below ILS minimums (all we have here is category 1). Tower Vis at 3/4, though. But, the forecast also doesn't show the prevailing conditions to go above mins until 0000Z, and only temporarily after 2200Z.

The following 2 METARs were issued while EGF4237 was in flight:

KMSN 312053Z 17006KT 1/4SM BR OVC001 07/07 A2960 RMK AO2 SFC VIS 2 SLP028 60000 T00670067 55025

KMSN 312100Z 18005KT 1SM BR OVC001 07/07 A2959 RMK AO2 SFC VIS 2

So, by the time they shot their first approach, the vis was reported above mins, but the ceiling still below. So is it only visibility that's required to be reported above mins for Part 121?

FWIW, they shot the ILS 18, and went missed at about 800 feet because they went full deflection on the localizer. (They reported to tower that there was something wrong with the localizer, "It went full deflection and we were on a pretty stable course.") So, they got vectored back around and shot the ILS 21 which has slightly higher mins (1137 1/2 vs. 1060/24 for the ILS 18) due to the offset localizer. But I guess they made it, I haven't heard them on frequency again.

If I recall correctly, ceiling was omitted from the minimums back in the 60's.

Bob Gardner