TORA, TODA, LDA, ASDA and NOTAMs

Runway declared distances are some of the most important numbers in airport NOTAMs. They decide how much runway is available for takeoff performance, rejected takeoff performance, and landing performance.

They are also easy to misread in raw text. A single NOTAM can say that a threshold is displaced, then list new TORA, TODA, ASDA and LDA values for both runway directions. If you read that as one generic runway restriction, you miss the operational detail.

That is why we now handle declared runway distances directly in Notamify Affected Elements V2 and Notam Globe.

What TORA, TODA, ASDA and LDA mean

The standard declared distances are:

The FAA AIM explains declared distances as operational distances that may be more or less than the physical runway length, because clearway, stopway, safety areas, object free areas and protection zones can all affect the declared value. It also states that when declared distances are published, pilots must use those declared distances instead of independently calculating from runway length.

Eurocontrol AIXM guidance uses the same concepts for structured runway declared distances and makes an important point for displacement: LDA is associated with the landing threshold or displaced threshold, while TORA, TODA and ASDA are takeoff distances associated with the takeoff start.

In practical terms:

• TORA, TODA and ASDA are measured from the takeoff start for that runway direction.
• LDA is measured from the landing threshold for that runway direction.
• A displaced threshold affects landing to that threshold, but it does not automatically move the takeoff start.
• A declared distance limit is not the same as a closed piece of pavement.

That last point matters for visualization. Declared distances are performance values. They should be shown as declared-distance markers, not as fake runway closures.

How NOTAMs change runway distances

Runway distance NOTAMs usually come in two forms.

First, a NOTAM may amend the declared distances directly:

RWY 08 TORA 1903M TODA 1963M ASDA 1903M LDA 2156M
RWY 26 TORA 1903M TODA 1963M ASDA 1903M LDA 1820M

Those values are authoritative for the NOTAM. We show the value exactly as structured in the affected element semantics, including the original unit. M is meters, not minutes. FT is feet.

Second, a NOTAM may move a threshold:

THR RWY 35 DISPLACED 180M

For Notamify, we now distinguish two structured subjects:

• THRESHOLD_DISPLACEMENT: the threshold is displaced by a value from the physical runway edge.
• THRESHOLD_FURTHER_DISPLACEMENT: the threshold is moved farther from the current threshold.

That distinction is important. If the NOTAM says the threshold is further displaced, the starting point is the current threshold, not automatically the physical runway edge.

How Notamify shows this now

Affected Elements V2 turns raw NOTAM text into structured runway changes. Instead of treating 1903M as a generic chip or parsing text in the UI, we now receive typed changes such as:

RWY 08: TORA 1903 m, TODA 1963 m, ASDA 1903 m, LDA 2156 m
RWY 26: threshold further displacement 375 m

That lets Notam Globe and the Affected Elements panel show the operational meaning, not just a list of values.

On the globe:

• TORA, TODA and ASDA labels are placed from the takeoff start for the runway direction.
• LDA is placed from the landing threshold.
• Threshold displacement is shown as a threshold change with a runway segment before the new landing threshold.
• The threshold segment is not styled as a pavement closure unless the NOTAM actually declares a closure.
• Markers use runway geometry and threshold geometry from the runway endpoint data where available.

In the Affected Elements UI:

• Runway distances are grouped as runway distances, not mixed into generic structured values.
• Meters and feet are formatted correctly.
• The related NOTAM count is based on the actual NOTAM id, not duplicated affected elements.
• The card makes clear whether the value is a declared distance or a threshold displacement.

Example: RPUX runway 35 threshold displacement

In this RPUX NOTAM, the affected elements include declared distances and a displaced threshold.

The important part is that LDA starts at the threshold. In the screenshot, runway 35 has a threshold displacement of 180 m and LDA of 625 m. The threshold marker and the LDA label are not the same concept:

• The threshold marker shows where landing to runway 35 begins.
• The LDA value shows the declared landing distance from that threshold.
• TORA, TODA and ASDA remain takeoff-distance values.

This is exactly the kind of NOTAM that gets messy if the UI only says "runway restricted." The pilot needs to know what changed, which runway direction it applies to, and whether it affects takeoff, landing, or both.

Example: NCRG Rarotonga declared distances

This NCRG NOTAM is a stronger example. It includes a further displaced threshold for runway 26 and amended declared distances for runway 08 and runway 26:

In Notam Globe, the labels are split by meaning:

• Runway 08 TORA, TODA and ASDA are shown from the runway 08 takeoff start.
• Runway 08 LDA is shown as a landing distance for runway 08.
• Runway 26 TORA, TODA and ASDA are shown from the runway 26 takeoff start.
• Runway 26 LDA is shown as a landing distance for runway 26.
• The runway 26 threshold further displacement is shown as a threshold change, with a highlight arrow from the previous threshold position to the new position when the threshold label is selected.

That separation is the important product decision. We do not want a single overloaded tooltip where a displaced threshold, LDA, TORA and ASDA all look like the same kind of value. They are not the same kind of value.

Why Affected Elements V2 matters

Most NOTAM tools still treat this as text. The user sees the raw paragraph, maybe a short AI summary, and has to reason through the runway geometry mentally.

Affected Elements V2 is different because it gives Notamify typed operational structure:

• runway direction
• effect
• declared distance subject
• distance value
• unit
• threshold displacement subject
• operating conditions and exceptions

That structure powers the UI. It lets us show the declared distances in a clean table, place the labels on the globe, and explain the meaning in the tooltip without turning the popup into a wall of chips.

For airport teams, dispatchers, pilots and software teams using the Notamify API, this is where graphical NOTAMs become more than drawing shapes. The map is reading the same structured affected element model that the cards, filters, alerts and API can read.

This is also one of many Notamify efforts to extract every single useful piece of operational data from NOTAMs and make it usable in Skymerse, our Autopilot for Flight Operations.

The practical rule

When a NOTAM declares TORA, TODA, ASDA or LDA, Notamify treats the declared value as the value to show.

When a NOTAM changes a threshold, Notamify treats that as threshold geometry:

• THRESHOLD_DISPLACEMENT is from the runway edge.
• THRESHOLD_FURTHER_DISPLACEMENT is from the current threshold.
• LDA is measured from the resulting landing threshold.
• TORA, TODA and ASDA are not tied to the landing threshold.

This is the level of precision NOTAM interfaces need. Raw text remains the source, but structured Affected Elements V2 makes the operational meaning visible.

Sources

• FAA AIM 4-3-6, Use of Runways and Declared Distances
• FAA AIM 2-3-3, Runway Markings
• Eurocontrol AIXM, Declared Distances