What+are+safety+nets

7/17/2019 What+are+safety+nets

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Safety nets in ATM

• Information released by:

The European Organization for the Safety of

Air Navigation (EUO!ONTO"#

$repared by:

A%$irhadi

&%'arirhian



What are safety nets?

• Even the safest systems fail.

Safety nets help prevent imminent or actualhazardous situations from developing into

major incidents or even accidents. ndoing so! they provide a "comfort zone# forthe human actors in the overall system. n

addition! they help $eep the societaloutcome of aviation operations %ithinaccepta&le limits



What are safety nets?

• Safety nets are the last system safetydefences against accidents.

They are intended to provide timely alertsto air traffic controllers or pilots of anincreased ris$ to flight safety. As theimpact of accidents in aviation is high!

multiple system safety defences areprovided! including redundant safety nets.



Safety nets are either ground'

&ased or air&orne(

• )round*based safety nets are an

integral part of the ATM system.

•)sing primarily ATS surveillance data!they provide %arning times of up to t%o

minutes. )pon receiving an alert! air traffic

controllers are e*pected to immediately

assess the situation and ta$e appropriateaction.



Safety nets are either ground'

&ased or air&orne(

• Airborne safety nets provide alerts and

resolution advisories directly to the pilots.

Warning times are generally shorter! up to

+, seconds.

• -ilots are e*pected to immediately ta$e

appropriate avoiding action.



mportant point

• itis important that air traffic controllers andpilots are a%are of ho% safety nets interact.

• ontrary to e*pectations! ground'&ased and

air&orne safety nets do not al%ays alert inse/uence. They operate independently. 0orsome situations! in particular in the case ofsudden or une*pected manoeuvres! they %ill

alert at a&out the same time or in anune*pected se/uence.



Why are safety nets needed?

• Safety is paramount in aviation1 under thehicago "onvention on ivil Aviation#!States are re/uired to provide a safe Air

Traffic Service 2ATS3 %ithin their definedairspace. Although re/uiring sophisticatedtechnical infrastructure and automation!the provision of ATS is a human'centredactivity and %ill remain so for many years.



Safety net as an assistance

• Safety nets should not change the normal

%ay of %or$ing of air traffic controllers or

pilots. Safety nets are there to provide an

additional safety margin on top of the

inherently safe provision of ATS and

aviation operations. They have &een

demonstrated to deliver additional ris$reduction up to a factor ten.



Which safety nets must &e

implemented?

• 0our ground'&ased safety nets

must &e implemented for

air&orne phases of flight. Safetynets for surface movements are

&eyond the scope of this 4uide.The covered safety nets are(



STA

• Short Term !onflit Alert (ST!A# *

assists the controller in preventing

collision &et%een aircraft &ygenerating! in a timely manner! an

alert of a potential or actual

infringement of separation minima.



A-W

• Area $ro+imity ,arning (A$,#

%arns the controller a&out

unauthorized penetration of anairspace volume &y generating! in a

timely manner! an alert of a potential

or actual infringement of the re/uiredspacing to that airspace volume.



MSAW

• &inimum Safe Altitude ,arning

(&SA,#

Warns the controller a&outincreased ris$ of controlled flight into

terrain accidents &y generating! in a

timely manner! an alert of aircraftpro*imity to terrain or o&stacles.



A-M

• . Approah $ath &onitor (A$&#

Warns the controller a&out increased

ris$ of controlled flight into terrainaccidents &y generating! in a timely

manner! an alert of aircraft pro*imity to

terrain or o&stacles during finalapproach.



Safety net &enefits

• ommon! /uantified performance characteristics

for safety are not 2yet3 esta&lished. 5o%ever!

several ATS providers 6eport signifiant

redutions in the number of inidentso&served after introducing or improving STA in

particular. 0or e*ample! the Maastricht )pper

Area ontrol entre annual report sho%s that in

7,,8 there %ere three ategory 9 incidents %ith ATS contri&ution compared to eight in each of

the three preceding years.



)ood to -no.

• Starting %ith the 7,:,'7,:+

cycle! the E- %ill &e

renamed( European SingleS$y mplementation 2ESS-3.



Areas of concern



W5E6E A;< W5E;?



EUO!ONTO" Safety egulation

!ommission (S!# $oliy

• The ne% policy introduces a process 2assignment3 thataims to ensure sufficient transparency and tracea&ility inthe decision ma$ing process on the use of a ground

&ased safety net %hile esta&lishing accounta&ility for itsuse. The policy contains t%elve recommendations in thefollo%ing areas(

• Assignment1• apacity and Efficiency1

• 6is$ Assessment and Mitigation1• Training and A%areness1• 6educed Modes of =peration1 and• Achieved >evel of Safety





Safety nets in SESA6

• :. =ngoing deployment of &est practices for ground'&ased safety nets! %hich corresponds %ith the actionsdescri&ed in this 4uide1 and

• 7. Enhanced AAS through use of Autopilot0light

<irector! %hich corresponds %ith features offered &y Air&us on ne% aircraft.• SESA6 research %ill lead to t.o further improvement

steps in the /012*/0/0 timeframe:• @. <isplay of AAS 6esolution Advisories on air traffic

controller %or$ing positions 2$no%n as 6A <o%nlin$31 and• +. Enhancement of ground'&ased safety nets &y ma$inguse of improved surveillance infrastructure and do%nlin$ed aircraft parameters.



Safety nets in SESA6

And beyond /0/0 three further operational

improvement steps %ill follo%(

• . Adaptation of AAS to ne% separation

modes1

• B. Adaptation of STA to ne% separation

modes1 and

• 8. mprovement of compati&ility &et%een

air&orne and ground'&ased safety nets.



T5E SA0ETC ;ET >0E C>E

• <efining safety nets

The -ey ativity in this phase is

apturing the operational re3uirements. 9ecause of the

need to ta$e local factors fully into account!

no generic operational re/uirements are

included in the guidance material. n stead!

a detailed chec$ is included %hich covers

aspects to address



mplementing safety nets

• it is imperative that fitness*for purpose

is ensured through appropriate

verifiation

ativities 2revie%s! inspections! tests!

etc.3 throughout this phase.

• Seemingly trivial choices %ill have to &emade.



=ptimizing safety nets

• optimization is not a one*off ativity. t is thereforeessential that transfer of o%nership is preceded &yappropriate staff training and familiarization.

• Since optimization is a reurring proess! investment

in a safety net "test&ed# is %orth%hile. A complete"test&ed# %ill include tools to capture relevant encountersfrom surveillance data! encounter categorization tools!an accurate fast'time simulation model of the relevantsafety net! and tools to capture and visualize relevantmetrics from fast'time simulations.

• ;ote that enounter ategorization in particular %illal%ays &e a la&our'intensive activity that re/uires active

involvement of operational users.



=perating safety nets

• 9efore starting first operations! air traffiontrollers must reeive training4aimed at reating an appropriate level

of trust in the concerned safety net. Thetime'criticality of alerts and the need forimmediate attention or action must &e %ellunderstood! &ut also the situations in%hich safety nets are less effective



=perating safety nets

• n order to avoid the "ry Wolf#

syndrome! the number of nuisane

and false alerts must be redued toa minimum.

• Air traffic controllers should &e

encouraged to report une*pected andun%anted safety nets &ehavior and

feed&ac$ should al%ays &e provided.



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