Metar TAF and Airmets

Introduction 
The use of metars, tafs and airmets are the accepted ways to gather weather information for a commercial operation of a uas. The weather requirements for uas operations under part 107 include, a minimum of 3 statue miles of viability and must be 500 feet below and 2000 feet to the side of the clouds. 

Decoding a Metar and Taf
Figure 1. Metar and Taf for klaf on 11/8/19 at 2149 UTC
Lets start with decoding this metar,
 KLAF         The airport, Lafayette airport
 072054Z     Date and time 7th of the month, 2054 UTC
33013KT     Wind at 330 degrees true, 13 Knots
10SM          10 statute miles of visibility
 CLR 02/M09   Clear 20000 less than 90000
A 3037      Altimeter   30.37 inches HG
RMK         Remarks
AO2          Automated collection with precipitation sensor
SLP287
T002121089     Temperature  2.2 degrees Celsius dew point -8.9 degrees Celsius
55003

Then the taffs are decoded the same way,
KLAF     Airport Lafayette
071720Z 0718/0818  Forecast from 1800 to 1930
35011KT    Wind at 350 degrees true, 11 Knots
P65M     6+ statute miles visibility
BKN030  Broken clouds at 3000 AGL

FM071930    From 1930 to 2100
35011KT        Wind at 350 degrees true, 11 Knots
P6SM              6+ statute miles visibility
SCT035            Scattered clouds at 3500 ft agl

FM081100      From November 8th 2100Z to november 9th 1100Z
VRB04KT       Variable wind direction at 4 knots
P6SM               6+ statute miles visibility
SKC                 Scattered clouds


Airmets 
Figure 2. An Airmet on sky vector on November 8th
Figure 1 is an image depicting 2 airmets, the blue is an icing airmet and the green is a turbulence airmet. We are going to focus on the icing airmet


-           1 WAUS43 KKCI 072045
-           2 CHIZ WA 072045
-           3 AIRMET ZULU UPDT 6 FOR ICE AND FRZLVL VALID UNTIL 080300
-           4 AIRMET ICE...WI LM LS MI LH IN
-           5 FROM 60ESE YQT TO SSM TO YVV TO 30SE ECK TO 40NE FWA TO GIJ TO
-           6 70SE GRB TO 60WNW TVC TO 20NNW RHI TO 60E DLH TO 70SSW YQT TO
-           7 60ESE YQT
-           8 MOD ICE BLW 090. CONDS CONTG BYD 03Z THRU 09Z.
-           9 OTLK VALID 0300-0900Z...ICE ND MN
-           10 BOUNDED BY 70WNW INL-30SE FAR-50S ISN-50NNW ISN-70WNW INL
-           11 MOD ICE BTN 090 AND FL180. CONDS DVLPG 06-09Z. CONDS CONTG THRU
-           12 09Z.
-           10 FRZLVL...RANGING FROM SFC-110 ACRS AREA
-            11 MULT FRZLVL BLW 070 BOUNDED BY 20WNW ISN-20S BIS-60ENE DPR-
-            12 60ESE PIR-30S FSD-70S FSD-50N ONL-60S PIR-30SSW DPR-30NNW
-            13 DPR-50S DIK-80SW DIK-20WNW ISN
-            14 MULT FRZLVL BLW 110 BOUNDED BY 60SW FSD-70S FSD-40NE OBH-20NW
-            15 MCI-30NW PXV-50S TTH-60WSW HNN-40N HMV-40WNW HMV-RZC-OSW-
-            16 50W LBL-GLD-40E AKO-30N LBF-40E LBF-60SW FSD
-            17 SFC ALG 50S GLD-50SW ICT
-            18 SFC ALG 40SE OSW-50SE FAM-30W IIU-20E CVG
-            19 040 ALG 40SE BWG-40W BKW
-            20 040 ALG 40SSW MCK-20ENE LBL
Above is the information copied over from the airmet, it can be translated to describe the area that is impacted by those conditions. Lines 1 and 2 describe the airport selected and the time the information was gathered. Lines 3 and 4 describe when the forcast is valid and where in a broad term it is in effect. Lines 5-7 give the location of icing, lines 8-10 give the locations of mod icing, lines 11-20 describe where it is below freezing level.
Discussion
While it might seem weird to use weather, that in its self can be a challenge to understand, this is important to use because it is the only approved weather source for aviation operations in the US. Another thing is that some uav operations like inspecting towers can create issues as at that altitude you could have icing conditions, and could get ice on the props, causing the uav to crash. I have personally experienced icing conditions with a fixed wing rc plane while flying in a freezing fog as a hobbyist, it caused the motor to seize in flight and a dead stick landing had to be carried out.
Conclusion
In conclusion aviation weather, metars, tafs, and airmets are important to understand because the weather information is of a higher quality and more acceptable for use for operations in the national airspace.


Comments

Post a Comment

Popular posts from this blog

Setting up a vtol in mission planner

Image
Introduction Setting up a vertical take off or landing (VTOL) uav is one of the more complex aspects of mission planner, for programming a pix hawk flight controller. The vtol that will be set up in this blog is a 2.5 meter wingspan, custom quad rotor, with all four motors tilting uav. Figure 1. A screen capture of the firmware installation page of mission planner  To begin install arduplane on your pixhawk, using the install firmware page in mission planner, figure 1 shows the pop up window that should appear. Next once the firmware is installed go through each of the settings of the mandatory setup, including the accelerometer calibration, compass calibration and the radio calibration, but skip the servo output for now. The next step is going to the full parameter list under the configuring and tuning tab, and enable Qplane, which stands for quadplane, and allows for all the vtol settings to be shown. Then the frame style and setup has to be configured, these have t...
Read more

DoakBurn (Again)

Image
 Introduction The goal of this lab was to use ArcGIS Pro to view the various band stacks of orthomosaic imagery and a normalized difference vegetation index (NIVD). The data was collected by Dr.Hupy, William Weldon and Zack Miller, and the data was of a controlled burn with multispectral cameras. Methods The methods of this lab was to look at the areas that were burned and compare them to the areas around them that were not burned. This could be done with RGB, or band stacking for the imagery, which allows the ability to see things that are not able to be seen with the human eye.  Metadata from the Flight Vehicle: Bramor PPX Sensor: Altum Flight Number: 2 Takeoff Time: 12:18 Pm Landing Time: 12:35 Pm Altitude (m): 121 Sensor Angle: NADIR Results  The data collected with the band stacking shows the differences between the pre-burn and post-burn data. Figure 1,2,4,5,6,9 are in a 5,3,2 band stack, meaning the red represents near-infrared, the green represents th...
Read more

Designing a Vtol Mechanism from scratch

Image
Introduction A project that I have been working on needed a Vertical takeoff or landing (VTOL)  tilt mechanism for the the front 2 motors, so here is how I went about designing and testing it. It can be challenging to hand launch a twin motor plane as you have to worry about both prop disc areas, while managing controls, and adding a vtol system can allow for operations where a wheel based takeoff is not a possibility  The specifications of the propulsion system are a Emax 2213-935KV brushless motor, that spins a 8045 prop, with a spider 20apm opto esc, using a 4 lithium polymer cell battery. This power systems is typically used in quad copters such as a dji flamewheel 450. The servos for tilting the motor varied depending on the design of the tilting mechanism. Figure 1. A dji flamewheel 450 quadcopter, with a propulsion system similar to the VTOL's system Goals  The goals of this project was to be able to develop a vtol tilt system for a uav that ...
Read more