TAF performance

Oct 2018 Jan 2019 Apr 2019 Jul 2019 Oct 20190.82

0.84

0.86

0.88

0.90

0.92

0.94

0.96

0.98

Latest CV34 value:0.895

SQI CompositeCivil 15 Composite Civil 34 Composite Target (0.878)

Performance of UK Civil aviationweather forecasts:November 2019

Monthly verification of the TAFs issued by the Met Office is undertaken. These statistics are a useful indicator onhow accurate these TAFs are, and consequently how valuable they are to airlines and pilots.

The Met Office TAF verification system considers various cloud and visibility thresholds to determine a ’ServiceQuality Index’ (SQI) score. The values obtained from the calculation range from 0 to 1, where 1 indicates perfectforecasts, the value we aspire to.

Results from a selection of airports (as agreed with the Civil Aviation Authority (CAA)) are provided in the graphsbelow. Also shown is a composite score, which is a result generated by combining the results from a defined listof airports (Note: This is not simply an average of all the SQI scores). The SQI composite performance target,as agreed with the CAA, is indicated. Scores are updated monthly, and are displayed here as 12-month rollingmeans.

Oct 2018 Jan 2019 Apr 2019 Jul 2019 Oct 20190.82

0.84

0.86

0.88

0.90

0.92

0.94

0.96

0.98SQI: Scotland West Region

Civil 34 CompositeEGPF

EGPKEGPO

Target

Oct 2018 Jan 2019 Apr 2019 Jul 2019 Oct 20190.82

0.84

0.86

0.88

0.90

0.92

0.94

0.96

0.98SQI: Scotland East Region

Civil 34 CompositeEGPH

EGPDEGPE

EGPBEGPM

EGPA Target

Oct 2018 Jan 2019 Apr 2019 Jul 2019 Oct 20190.82

0.84

0.86

0.88

0.90

0.92

0.94

0.96

0.98SQI: N. Ireland Region

Civil 34 CompositeEGAA

EGACEGAE

Target

Oct 2018 Jan 2019 Apr 2019 Jul 2019 Oct 20190.82

0.84

0.86

0.88

0.90

0.92

0.94

0.96

0.98SQI: LTMA Region

Civil 34 CompositeEGLL

EGKKEGSS

EGGWEGLC

EGHIEGMC

EGSHTarget

Oct 2018 Jan 2019 Apr 2019 Jul 2019 Oct 20190.82

0.84

0.86

0.88

0.90

0.92

0.94

0.96

0.98SQI: Airfields1 Region

Civil 34 CompositeEGCC

EGGPEGNT

EGNMEGCN

EGNJEGNV

Target

Oct 2018 Jan 2019 Apr 2019 Jul 2019 Oct 20190.82

0.84

0.86

0.88

0.90

0.92

0.94

0.96

0.98SQI: Airfields2 Region

Civil 34 CompositeEGBB

EGGDEGNX

EGFFEGTE

EGHHEGHQ

Target

2011 2012 2013 2014 2015 2016 2017 2018 20192.60

2.80

3.00

3.20

3.40

3.60

3.80

4.00

Roo

tMea

nS

quar

eVe

ctor

Err

or

Latest value:2.91 m/s

Northern Hemisphere T+24 Wind (m/s) at 250hPaMonthlyRolling 12-month meanTarget

2011 2012 2013 2014 2015 2016 2017 2018 20190.50

0.55

0.60

0.65

0.70

0.75

Roo

tMea

nS

quar

eE

rror

Latest value:0.57 K

Global Model performance

Northern Hemisphere T+24 Temperature (K) at 250hPaMonthlyRolling 12-month meanTarget

Accurate forecasting of upper wind and temperature is essential for safe and economic civil international airtravel. The CAA have agreed targets (shown below) with the Met Office for day 1 forecasts (T+24) takenfrom the 00Z and 12Z operational Global model runs for results at 250hPa (which equates to FL340) over theNorthern Hemisphere (90N-20N). The graphs below display the accuracy of these two fields with the smallerthe error being the better value forecast to airline operators.

Performance measure (set for 12-month mean values): ≤ 3.40m/s for Wind and ≤ 0.63K for Temperature.

Dec2018

Feb2019

Apr2019

Jun2019

Aug2019

Oct2019

0

1

2

3

4

Timeliness of BUFR data

Count of occasions transmission time target exceeded00Z 06Z 12Z 18Z

As a World Area Forecast Centre (WAFC), significant weather charts to support Global air travel are provided by theMet Office. The timely delivery of the data used to compile these charts is important for flight planning. The graphsbelow show the number of occasions per month that a significant weather chart has been transmitted late, and fromwhich model run it occurred from.

Performance measure: In no more than 3 instances per quarter (99.2%) should the transmission time of 7hrs 00minsbe exceeded from any of the four model runs.

Aberdeen Heathrow Manchester Norwich Scatsta

August 2019

Sumburgh

Timely TREND forecasts Late/missing TREND

Aberdeen Heathrow Manchester Norwich Scatsta

September 2019

Sumburgh

Aberdeen Heathrow Manchester Norwich Scatsta

October 2019

Sumburgh

Aberdeen Heathrow Manchester Norwich Scatsta

November 2019

Timeliness of TREND forecasts

Sumburgh

TRENDs are 2 hour ’landing forecasts’ which get appended to METAR reports at selected UK airports. Thetarget is for appending a trend within 7 minutes from the validity time of the observation (nominally 3 minutesfrom receipt of the METAR).

The pie charts below represent how six sites have performed over the most recent four months, with with thetable at the bottom showing the green area in the charts in percentage terms.

Performance measure: Append a TREND to the METAR on ≥ 85% of occasions (12-month rolling mean)

August 2019 September 2019 October 2019 November 2019Aberdeen (EGPD) 93.3% 92.9% 89.3% 90.1%Heathrow (EGLL) 96.5% 95.4% 93.7% 93.6%Manchester (EGCC) 95.5% 95.6% 92.7% 93.9%Norwich (EGSH) 95.2% 95.2% 94.4% 94.0%Scatsta (EGPM) 90.1% 90.8% 87.4% 89.4%Sumburgh (EGPB) 91.9% 87.9% 85.8% 84.6%12-month rolling mean 94.3% 94.2% 93.8% 93.6%

TAF timeliness

Reliable provision of TAFs are important to airlines and pilots, to ensure they are fully briefed on theexpected weather conditions at an airport upon arrival.

Around 280 TAFs per day are issued by the Met Office, and a percentage of all these TAFs generatedin time for inclusion into bulletins generated by NATS are measured. Results from the most recentfour months are shown below.

Performance measure: At least 95% timely receipt.

August 2019 September 2019 October 2019 November 2019% timely 98.2% 96.7% 96.3% 95.4%

Generated December 2019 for November 2019 results© Crown copyright 2019

Met Office Tel: 0870 900 0100FitzRoy Road, Exeter Fax: 0870 900 5050Devon EX1 3PB enquiries@metoffice.gov.ukUnited Kingdom www.metoffice.gov.uk